diff --git a/src/Symfony/Component/Form/CHANGELOG.md b/src/Symfony/Component/Form/CHANGELOG.md
index a19b52f8f937..dc6664600556 100644
--- a/src/Symfony/Component/Form/CHANGELOG.md
+++ b/src/Symfony/Component/Form/CHANGELOG.md
@@ -149,9 +149,8 @@ CHANGELOG
  * fixed: the "data" option supersedes default values from the model
  * changed DateType to refer to the "format" option for calculating the year and day choices instead
    of padding them automatically
- * [BC BREAK] DateType defaults to the format "yyyy-MM-dd" now in order to support
-   the HTML 5 date field out of the box
+ * [BC BREAK] DateType defaults to the format "yyyy-MM-dd" now if the widget is
+   "single_text", in order to support the HTML 5 date field out of the box
  * added the option "format" to DateTimeType
- * [BC BREAK] DateTimeType defaults to the format "yyyy-MM-dd'T'HH:mm:ss" now. This
-   is almost identical to the pattern of the HTML 5 datetime input, but not quite,
-   because ICU cannot generate RFC 3339 dates (which have a timezone suffix).
+ * [BC BREAK] DateTimeType now outputs RFC 3339 dates by default, as generated and
+   consumed by HTML5 browsers, if the widget is "single_text"
diff --git a/src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeToRfc3339Transformer.php b/src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeToRfc3339Transformer.php
new file mode 100644
index 000000000000..406275991362
--- /dev/null
+++ b/src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeToRfc3339Transformer.php
@@ -0,0 +1,80 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Form\Extension\Core\DataTransformer;
+
+use Symfony\Component\Form\Exception\UnexpectedTypeException;
+use Symfony\Component\Form\Exception\TransformationFailedException;
+
+/**
+ * @author Bernhard Schussek <bschussek@gmail.com>
+ */
+class DateTimeToRfc3339Transformer extends BaseDateTimeTransformer
+{
+    /**
+     * {@inheritDoc}
+     */
+    public function transform($dateTime)
+    {
+        if (null === $dateTime) {
+            return '';
+        }
+
+        if (!$dateTime instanceof \DateTime) {
+            throw new UnexpectedTypeException($dateTime, '\DateTime');
+        }
+
+        if ($this->inputTimezone !== $this->outputTimezone) {
+            $dateTime = clone $dateTime;
+            $dateTime->setTimezone(new \DateTimeZone($this->outputTimezone));
+        }
+
+        return preg_replace('/\+00:00$/', 'Z', $dateTime->format('c'));
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function reverseTransform($rfc3339)
+    {
+        if (!is_string($rfc3339)) {
+            throw new UnexpectedTypeException($rfc3339, 'string');
+        }
+
+        if ('' === $rfc3339) {
+            return null;
+        }
+
+
+        $dateTime = new \DateTime($rfc3339);
+
+        if ($this->outputTimezone !== $this->inputTimezone) {
+            try {
+                $dateTime->setTimezone(new \DateTimeZone($this->inputTimezone));
+            } catch (\Exception $e) {
+                throw new TransformationFailedException($e->getMessage(), $e->getCode(), $e);
+            }
+        }
+
+        if (preg_match('/(\d{4})-(\d{2})-(\d{2})/', $rfc3339, $matches)) {
+            if (!checkdate($matches[2], $matches[3], $matches[1])) {
+                throw new TransformationFailedException(sprintf(
+                    'The date "%s-%s-%s" is not a valid date.',
+                    $matches[1],
+                    $matches[2],
+                    $matches[3]
+                ));
+            }
+        }
+
+        return $dateTime;
+    }
+}
diff --git a/src/Symfony/Component/Form/Extension/Core/Type/DateTimeType.php b/src/Symfony/Component/Form/Extension/Core/Type/DateTimeType.php
index 233c2294d744..eff633e09f72 100644
--- a/src/Symfony/Component/Form/Extension/Core/Type/DateTimeType.php
+++ b/src/Symfony/Component/Form/Extension/Core/Type/DateTimeType.php
@@ -22,6 +22,7 @@
 use Symfony\Component\Form\Extension\Core\DataTransformer\DateTimeToStringTransformer;
 use Symfony\Component\Form\Extension\Core\DataTransformer\DateTimeToLocalizedStringTransformer;
 use Symfony\Component\Form\Extension\Core\DataTransformer\DateTimeToTimestampTransformer;
+use Symfony\Component\Form\Extension\Core\DataTransformer\DateTimeToRfc3339Transformer;
 use Symfony\Component\Form\Extension\Core\DataTransformer\ArrayToPartsTransformer;
 use Symfony\Component\OptionsResolver\Options;
 use Symfony\Component\OptionsResolver\OptionsResolverInterface;
@@ -44,8 +45,17 @@ class DateTimeType extends AbstractType
      * http://userguide.icu-project.org/formatparse/datetime#TOC-Date-Time-Format-Syntax
      * http://www.w3.org/TR/html-markup/input.datetime.html
      * http://tools.ietf.org/html/rfc3339
+     *
+     * An ICU ticket was created:
+     * http://icu-project.org/trac/ticket/9421
+     *
+     * To temporarily circumvent this issue, DateTimeToRfc3339Transformer is used
+     * when the format matches this constant.
+     *
+     * ("ZZZZZZ" is not recognized by ICU and used here to differentiate this
+     * pattern from custom patterns).
      */
-    const HTML5_FORMAT = "yyyy-MM-dd'T'HH:mm:ss";
+    const HTML5_FORMAT = "yyyy-MM-dd'T'HH:mm:ssZZZZZZ";
 
     private static $acceptedFormats = array(
         \IntlDateFormatter::FULL,
@@ -78,18 +88,25 @@ public function buildForm(FormBuilderInterface $builder, array $options)
         }
 
         if (null !== $pattern && (false === strpos($pattern, 'y') || false === strpos($pattern, 'M') || false === strpos($pattern, 'd') || false === strpos($pattern, 'H') || false === strpos($pattern, 'm'))) {
-            throw new InvalidOptionsException(sprintf('The "format" option should contain the patterns "y", "M", "d", "H" and "m". Its current value is "%s".', $pattern));
+            throw new InvalidOptionsException(sprintf('The "format" option should contain the letters "y", "M", "d", "H" and "m". Its current value is "%s".', $pattern));
         }
 
         if ('single_text' === $options['widget']) {
-            $builder->addViewTransformer(new DateTimeToLocalizedStringTransformer(
-                $options['data_timezone'],
-                $options['user_timezone'],
-                $dateFormat,
-                $timeFormat,
-                $calendar,
-                $pattern
-            ));
+            if (self::HTML5_FORMAT === $pattern) {
+                $builder->addViewTransformer(new DateTimeToRfc3339Transformer(
+                    $options['data_timezone'],
+                    $options['user_timezone']
+                ));
+            } else {
+                $builder->addViewTransformer(new DateTimeToLocalizedStringTransformer(
+                    $options['data_timezone'],
+                    $options['user_timezone'],
+                    $dateFormat,
+                    $timeFormat,
+                    $calendar,
+                    $pattern
+                ));
+            }
         } else {
             // Only pass a subset of the options to children
             $dateOptions = array_intersect_key($options, array_flip(array(
diff --git a/src/Symfony/Component/Form/Extension/Core/Type/DateType.php b/src/Symfony/Component/Form/Extension/Core/Type/DateType.php
index 4d86fdac4b57..d3d3b091362a 100644
--- a/src/Symfony/Component/Form/Extension/Core/Type/DateType.php
+++ b/src/Symfony/Component/Form/Extension/Core/Type/DateType.php
@@ -53,7 +53,7 @@ public function buildForm(FormBuilderInterface $builder, array $options)
         }
 
         if (null !== $pattern && (false === strpos($pattern, 'y') || false === strpos($pattern, 'M') || false === strpos($pattern, 'd'))) {
-            throw new InvalidOptionsException(sprintf('The "format" option should contain the patterns "y", "M" and "d". Its current value is "%s".', $pattern));
+            throw new InvalidOptionsException(sprintf('The "format" option should contain the letters "y", "M" and "d". Its current value is "%s".', $pattern));
         }
 
         if ('single_text' === $options['widget']) {
diff --git a/src/Symfony/Component/Form/Tests/AbstractLayoutTest.php b/src/Symfony/Component/Form/Tests/AbstractLayoutTest.php
index c9cc5e9135c4..549af044abbe 100644
--- a/src/Symfony/Component/Form/Tests/AbstractLayoutTest.php
+++ b/src/Symfony/Component/Form/Tests/AbstractLayoutTest.php
@@ -970,7 +970,7 @@ public function testDateTimeWithWidgetSingleText()
 '/input
     [@type="datetime"]
     [@name="name"]
-    [@value="2011-02-03T04:05:06"]
+    [@value="2011-02-03T04:05:06+01:00"]
 '
         );
     }
@@ -988,7 +988,7 @@ public function testDateTimeWithWidgetSingleTextIgnoreDateAndTimeWidgets()
 '/input
     [@type="datetime"]
     [@name="name"]
-    [@value="2011-02-03T04:05:06"]
+    [@value="2011-02-03T04:05:06+01:00"]
 '
         );
     }
diff --git a/src/Symfony/Component/Form/Tests/Extension/Core/DataTransformer/DateTimeToRfc3339TransformerTest.php b/src/Symfony/Component/Form/Tests/Extension/Core/DataTransformer/DateTimeToRfc3339TransformerTest.php
new file mode 100644
index 000000000000..40195cb517d3
--- /dev/null
+++ b/src/Symfony/Component/Form/Tests/Extension/Core/DataTransformer/DateTimeToRfc3339TransformerTest.php
@@ -0,0 +1,122 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Form\Tests\Extension\Core\DataTransformer;
+
+use Symfony\Component\Form\Extension\Core\DataTransformer\DateTimeToRfc3339Transformer;
+
+class DateTimeToRfc3339TransformerTest extends DateTimeTestCase
+{
+    protected $dateTime;
+    protected $dateTimeWithoutSeconds;
+
+    protected function setUp()
+    {
+        parent::setUp();
+
+        $this->dateTime = new \DateTime('2010-02-03 04:05:06 UTC');
+        $this->dateTimeWithoutSeconds = new \DateTime('2010-02-03 04:05:00 UTC');
+    }
+
+    protected function tearDown()
+    {
+        $this->dateTime = null;
+        $this->dateTimeWithoutSeconds = null;
+    }
+
+    public static function assertEquals($expected, $actual, $message = '', $delta = 0, $maxDepth = 10, $canonicalize = FALSE, $ignoreCase = FALSE)
+    {
+        if ($expected instanceof \DateTime && $actual instanceof \DateTime) {
+            $expected = $expected->format('c');
+            $actual = $actual->format('c');
+        }
+
+        parent::assertEquals($expected, $actual, $message, $delta, $maxDepth, $canonicalize, $ignoreCase);
+    }
+
+    public function allProvider()
+    {
+        return array(
+            array('UTC', 'UTC', '2010-02-03 04:05:06 UTC', '2010-02-03T04:05:06Z'),
+            array('UTC', 'UTC', null, ''),
+            array('America/New_York', 'Asia/Hong_Kong', '2010-02-03 04:05:06 America/New_York', '2010-02-03T17:05:06+08:00'),
+            array('America/New_York', 'Asia/Hong_Kong', null, ''),
+            array('UTC', 'Asia/Hong_Kong', '2010-02-03 04:05:06 UTC', '2010-02-03T12:05:06+08:00'),
+            array('America/New_York', 'UTC', '2010-02-03 04:05:06 America/New_York', '2010-02-03T09:05:06Z'),
+        );
+    }
+
+    public function transformProvider()
+    {
+        return $this->allProvider();
+    }
+
+    public function reverseTransformProvider()
+    {
+        return array_merge($this->allProvider(), array(
+            // format without seconds, as appears in some browsers
+            array('UTC', 'UTC', '2010-02-03 04:05:00 UTC', '2010-02-03T04:05Z'),
+            array('America/New_York', 'Asia/Hong_Kong', '2010-02-03 04:05:00 America/New_York', '2010-02-03T17:05+08:00'),
+        ));
+    }
+
+    /**
+     * @dataProvider transformProvider
+     */
+    public function testTransform($fromTz, $toTz, $from, $to)
+    {
+        $transformer = new DateTimeToRfc3339Transformer($fromTz, $toTz);
+
+        $this->assertSame($to, $transformer->transform(null !== $from ? new \DateTime($from) : null));
+    }
+
+    /**
+     * @expectedException Symfony\Component\Form\Exception\UnexpectedTypeException
+     */
+    public function testTransformRequiresValidDateTime()
+    {
+        $transformer = new DateTimeToRfc3339Transformer();
+        $transformer->transform('2010-01-01');
+    }
+
+    /**
+     * @dataProvider reverseTransformProvider
+     */
+    public function testReverseTransform($toTz, $fromTz, $to, $from)
+    {
+        $transformer = new DateTimeToRfc3339Transformer($toTz, $fromTz);
+
+        if (null !== $to) {
+            $this->assertDateTimeEquals(new \DateTime($to), $transformer->reverseTransform($from));
+        } else {
+            $this->assertSame($to, $transformer->reverseTransform($from));
+        }
+    }
+
+    /**
+     * @expectedException Symfony\Component\Form\Exception\UnexpectedTypeException
+     */
+    public function testReverseTransformRequiresString()
+    {
+        $transformer = new DateTimeToRfc3339Transformer();
+        $transformer->reverseTransform(12345);
+    }
+
+    /**
+     * @expectedException Symfony\Component\Form\Exception\TransformationFailedException
+     */
+    public function testReverseTransformWithNonExistingDate()
+    {
+        $transformer = new DateTimeToRfc3339Transformer('UTC', 'UTC');
+
+        var_dump($transformer->reverseTransform('2010-04-31T04:05Z'));
+    }
+}
diff --git a/src/Symfony/Component/Form/Tests/Extension/Core/Type/DateTimeTypeTest.php b/src/Symfony/Component/Form/Tests/Extension/Core/Type/DateTimeTypeTest.php
index e83d187fb7dc..ef31d7293595 100644
--- a/src/Symfony/Component/Form/Tests/Extension/Core/Type/DateTimeTypeTest.php
+++ b/src/Symfony/Component/Form/Tests/Extension/Core/Type/DateTimeTypeTest.php
@@ -165,12 +165,12 @@ public function testSubmit_differentTimezonesDateTime()
 
         $outputTime = new \DateTime('2010-06-02 03:04:00 Pacific/Tahiti');
 
-        $form->bind('2010-06-02T03:04:00');
+        $form->bind('2010-06-02T03:04:00-10:00');
 
         $outputTime->setTimezone(new \DateTimeZone('America/New_York'));
 
         $this->assertDateTimeEquals($outputTime, $form->getData());
-        $this->assertEquals('2010-06-02T03:04:00', $form->getViewData());
+        $this->assertEquals('2010-06-02T03:04:00-10:00', $form->getViewData());
     }
 
     public function testSubmit_stringSingleText()
@@ -182,10 +182,10 @@ public function testSubmit_stringSingleText()
             'widget' => 'single_text',
         ));
 
-        $form->bind('2010-06-02T03:04:00');
+        $form->bind('2010-06-02T03:04:00Z');
 
         $this->assertEquals('2010-06-02 03:04:00', $form->getData());
-        $this->assertEquals('2010-06-02T03:04:00', $form->getViewData());
+        $this->assertEquals('2010-06-02T03:04:00Z', $form->getViewData());
     }
 
     public function testSubmit_stringSingleText_withSeconds()
@@ -198,10 +198,10 @@ public function testSubmit_stringSingleText_withSeconds()
             'with_seconds' => true,
         ));
 
-        $form->bind('2010-06-02T03:04:05');
+        $form->bind('2010-06-02T03:04:05Z');
 
         $this->assertEquals('2010-06-02 03:04:05', $form->getData());
-        $this->assertEquals('2010-06-02T03:04:05', $form->getViewData());
+        $this->assertEquals('2010-06-02T03:04:05Z', $form->getViewData());
     }
 
     public function testSubmit_differentPattern()
@@ -355,4 +355,35 @@ public function testPassEmptyValueAsPartialArray_addNullIfRequired()
         $this->assertNull($view->get('time')->get('minute')->getVar('empty_value'));
         $this->assertSame('Empty second', $view->get('time')->get('second')->getVar('empty_value'));
     }
+
+    public function testPassHtml5TypeIfSingleTextAndHtml5Format()
+    {
+        $form = $this->factory->create('datetime', null, array(
+            'widget' => 'single_text',
+        ));
+
+        $view = $form->createView();
+        $this->assertSame('datetime', $view->getVar('type'));
+    }
+
+    public function testDontPassHtml5TypeIfNotHtml5Format()
+    {
+        $form = $this->factory->create('datetime', null, array(
+            'widget' => 'single_text',
+            'format' => 'yyyy-MM-dd HH:mm',
+        ));
+
+        $view = $form->createView();
+        $this->assertNull($view->getVar('datetime'));
+    }
+
+    public function testDontPassHtml5TypeIfNotSingleText()
+    {
+        $form = $this->factory->create('datetime', null, array(
+            'widget' => 'text',
+        ));
+
+        $view = $form->createView();
+        $this->assertNull($view->getVar('type'));
+    }
 }
diff --git a/src/Symfony/Component/Form/Tests/Extension/Core/Type/DateTypeTest.php b/src/Symfony/Component/Form/Tests/Extension/Core/Type/DateTypeTest.php
index f1f117ce26dd..ca7218a9a8ae 100644
--- a/src/Symfony/Component/Form/Tests/Extension/Core/Type/DateTypeTest.php
+++ b/src/Symfony/Component/Form/Tests/Extension/Core/Type/DateTypeTest.php
@@ -677,7 +677,7 @@ public function testDontPassHtml5TypeIfNotHtml5Format()
         $this->assertNull($view->getVar('type'));
     }
 
-    public function testPassHtml5TypeIfNotSingleText()
+    public function testDontPassHtml5TypeIfNotSingleText()
     {
         $form = $this->factory->create('date', null, array(
             'widget' => 'text',