diff --git a/PostgresqlExtensionsGrailsPlugin.groovy b/PostgresqlExtensionsGrailsPlugin.groovy
index 2e07b69..65148a1 100644
--- a/PostgresqlExtensionsGrailsPlugin.groovy
+++ b/PostgresqlExtensionsGrailsPlugin.groovy
@@ -3,7 +3,7 @@ import net.kaleidos.hibernate.postgresql.criteria.HstoreCriterias
 
 class PostgresqlExtensionsGrailsPlugin {
     // the plugin version
-    def version = "4.0.0"
+    def version = "4.1.0"
     // the version or versions of Grails the plugin is designed for
     def grailsVersion = "2.0 > *"
     // the other plugins this plugin depends on
@@ -25,7 +25,7 @@ class PostgresqlExtensionsGrailsPlugin {
     def author = "Iván López"
     def authorEmail = "lopez.ivan@gmail.com"
     def description = '''\
-This plugin provides hibernate user types to support for Postgresql Native Types like Arrays, HStores, JSON,... as well as new criterias to query this native types
+This plugin provides hibernate user types to support for Postgresql Native Types like Array, HStore, JSON,... as well as new criterias to query this native types
 '''
 
     // URL to the plugin's documentation
diff --git a/README.md b/README.md
index e4d7ed8..bcc1239 100644
--- a/README.md
+++ b/README.md
@@ -5,9 +5,9 @@ Grails Postgresql Extensions
 [![Build Status](https://travis-ci.org/kaleidos/grails-postgresql-extensions.svg?branch=master)](https://travis-ci.org/kaleidos/grails-postgresql-extensions)
 [![Coverage Status](https://coveralls.io/repos/kaleidos/grails-postgresql-extensions/badge.png?branch=master)](https://coveralls.io/r/kaleidos/grails-postgresql-extensions?branch=master)
 
-This is a grails plugin that provides hibernate user types to use postgresql native types such as arrays, hstores, json,... from a Grails application. It also provides new criterias to query this new native types.
+This is a grails plugin that provides hibernate user types to use Postgresql native types such as Array, Hstore, Json,... from a Grails application. It also provides new criterias to query this new native types.
 
-Currently the plugin supports arrays and hstore and some query methods has been implemented. More native types and query methods will be added in the future.
+Currently the plugin supports array, hstore and json fields as well as some query methods. More native types and query methods will be added in the future.
 
 * [Installation](#installation)
 * [Configuration](#configuration)
@@ -30,6 +30,7 @@ Currently the plugin supports arrays and hstore and some query methods has been
         * [Contains Key](#contains-key)
         * [Contains](#contains-1)
         * [Is Contained](#is-contained-1)
+  * [JSON](#json)
 * [Authors](#authors)
 * [Release Notes](#release-notes)
 
@@ -409,6 +410,47 @@ testAttributes = ["1" : "a", "2" : "b"]
 ```
 This criteria can also be used to look for exact matches
 
+
+### JSON
+
+Currently the Json support is only available in Grails 2.2.5 and 2.3.1+. Just like with the Hstore support, it's not possible to use a Map in domain classes with old Grails versions and be able to set the database type for the Map.
+
+To define a json field you only have to define a `Map` field and use the `JsonMapType` hibernate user type.
+
+```groovy
+import net.kaleidos.hibernate.usertype.JsonMapType
+
+class TestMapJson {
+
+    Map data
+
+    static constraints = {
+    }
+    static mapping = {
+        data type: JsonMapType
+    }
+}
+```
+
+#### Using Json
+
+Now you can create and instance of the domain class:
+
+```groovy
+def instance = new TestMapJson(data: [name: "Iván", age: 34, hasChilds: true, childs: [[name: 'Judith', age: 7], [name: 'Adriana', age: 4]]])
+instance.save()
+```
+
+```
+=# select * from test_map_json;
+
+ id | version | data
+----+---------+-------------------------------------------------------------------------------------------------------------
+  1 |       0 | {"hasChilds":true,"age":34,"name":"Iván","childs":[{"name":"Judith","age":7},{"name":"Adriana","age":4}]}
+
+As you can see the plugin converts to Json automatically the attributes and the lists in the map type.
+
+
 Authors
 -------
 
@@ -423,9 +465,10 @@ Collaborations are appreciated :-)
 Release Notes
 -------------
 
-* [4.0.0] - 18/Jul/2014 - Version compatible with Hibernate 4.x
-* [3.0.0] - 18/Jul/2014 - Version compatible with Hibernate 3.x
-* [0.9](https://github.com/kaleidos/grails-postgresql-extensions/issues?milestone=1) - 16/Jun/2014 - Add new array criterias: pgArrayEquals, pgArrayNotEquals
+* 4.1.0 - 23/Jul/2014 - Add JSON support. It's now possible to store and read domain classes with map types persisted to json.
+* 4.0.0 - 18/Jul/2014 - Version compatible with Hibernate 4.x.
+* 3.0.0 - 18/Jul/2014 - Version compatible with Hibernate 3.x.
+* [0.9](https://github.com/kaleidos/grails-postgresql-extensions/issues?milestone=1) - 16/Jun/2014 - Add new array criterias: pgArrayEquals, pgArrayNotEquals.
 * 0.8.1 - 24/Apr/2014 - Fix NPE when array is null.
 * 0.8 - 24/Apr/2014 - Added support for Double and Float arrays. Refactored the ArrayType to be used as a parametrized type.
 * 0.7 - Unreleased - New HstoreMapType and update plugin to Grails 2.2.5.
diff --git a/grails-app/conf/BuildConfig.groovy b/grails-app/conf/BuildConfig.groovy
index 5a9b1e0..ae87eba 100644
--- a/grails-app/conf/BuildConfig.groovy
+++ b/grails-app/conf/BuildConfig.groovy
@@ -37,6 +37,8 @@ grails.project.dependency.resolution = {
         test "org.springframework:spring-expression:$springVersion"
         test "org.springframework:spring-aop:$springVersion"
 
+        compile 'com.google.code.gson:gson:2.2.4'
+
         // Coveralls plugin
         build 'org.apache.httpcomponents:httpcore:4.3.2'
         build 'org.apache.httpcomponents:httpclient:4.3.2'
diff --git a/grails-app/domain/test/json/TestMapJson.groovy b/grails-app/domain/test/json/TestMapJson.groovy
new file mode 100644
index 0000000..6aa1eee
--- /dev/null
+++ b/grails-app/domain/test/json/TestMapJson.groovy
@@ -0,0 +1,14 @@
+package test.json
+
+import net.kaleidos.hibernate.usertype.JsonMapType
+
+class TestMapJson {
+
+    Map data
+
+    static constraints = {
+    }
+    static mapping = {
+        data type: JsonMapType
+    }
+}
\ No newline at end of file
diff --git a/src/java/net/kaleidos/hibernate/PostgresqlExtensionsDialect.java b/src/java/net/kaleidos/hibernate/PostgresqlExtensionsDialect.java
index 7160f1a..aea299d 100644
--- a/src/java/net/kaleidos/hibernate/PostgresqlExtensionsDialect.java
+++ b/src/java/net/kaleidos/hibernate/PostgresqlExtensionsDialect.java
@@ -2,6 +2,7 @@
 
 import net.kaleidos.hibernate.usertype.ArrayType;
 import net.kaleidos.hibernate.usertype.HstoreType;
+import net.kaleidos.hibernate.usertype.JsonMapType;
 import org.hibernate.dialect.Dialect;
 import org.hibernate.dialect.PostgreSQL81Dialect;
 import org.hibernate.id.PersistentIdentifierGenerator;
@@ -26,6 +27,7 @@ public PostgresqlExtensionsDialect() {
         registerColumnType(ArrayType.DOUBLE_ARRAY, "float8[]");
         registerColumnType(ArrayType.FLOAT_ARRAY, "float[]");
         registerColumnType(HstoreType.SQLTYPE, "hstore");
+        registerColumnType(JsonMapType.SQLTYPE, "json");
     }
 
     /**
diff --git a/src/java/net/kaleidos/hibernate/usertype/JsonMapType.java b/src/java/net/kaleidos/hibernate/usertype/JsonMapType.java
new file mode 100644
index 0000000..df71754
--- /dev/null
+++ b/src/java/net/kaleidos/hibernate/usertype/JsonMapType.java
@@ -0,0 +1,95 @@
+package net.kaleidos.hibernate.usertype;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import org.apache.commons.lang.ObjectUtils;
+import org.hibernate.HibernateException;
+import org.hibernate.engine.spi.SessionImplementor;
+import org.hibernate.usertype.UserType;
+
+import java.io.Serializable;
+import java.lang.reflect.Type;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Types;
+import java.util.HashMap;
+import java.util.Map;
+
+public class JsonMapType implements UserType {
+
+    public static int SQLTYPE = 90021;
+
+    private final Type userType = Map.class;
+
+    private final Gson gson = new GsonBuilder().create();
+
+    @Override
+    public int[] sqlTypes() {
+        return new int[]{SQLTYPE};
+    }
+
+    @Override
+    public Class returnedClass() {
+        return userType.getClass();
+    }
+
+    @Override
+    public boolean equals(Object x, Object y) throws HibernateException {
+        return ObjectUtils.equals(x, y);
+    }
+
+    @Override
+    public int hashCode(Object x) throws HibernateException {
+        return x == null ? 0 : x.hashCode();
+    }
+
+    @Override
+    public Object nullSafeGet(ResultSet rs, String[] names, SessionImplementor session, Object owner) throws HibernateException, SQLException {
+        String jsonString = rs.getString(names[0]);
+        return gson.fromJson(jsonString, userType);
+    }
+
+    @Override
+    public void nullSafeSet(PreparedStatement st, Object value, int index, SessionImplementor session) throws HibernateException, SQLException {
+        if (value == null) {
+            st.setNull(index, Types.OTHER);
+        } else {
+            st.setObject(index, gson.toJson(value, userType), Types.OTHER);
+        }
+    }
+
+    @Override
+    public Object deepCopy(Object value) throws HibernateException {
+        if (value != null) {
+            Map m = (Map) value;
+
+            if (m == null) {
+                m = new HashMap();
+            }
+            return new HashMap(m);
+        } else {
+            return null;
+        }
+    }
+
+    @Override
+    public boolean isMutable() {
+        return true;
+    }
+
+    @Override
+    public Serializable disassemble(Object value) throws HibernateException {
+        return gson.toJson(value, userType);
+    }
+
+    @Override
+    public Object assemble(Serializable cached, Object owner) throws HibernateException {
+        return gson.fromJson((String) cached, userType);
+    }
+
+    @Override
+    public Object replace(Object original, Object target, Object owner) throws HibernateException {
+        return original;
+    }
+}
\ No newline at end of file
diff --git a/test/integration/net/kaleidos/hibernate/json/PostgresqlJsonMapDomainIntegrationSpec.groovy b/test/integration/net/kaleidos/hibernate/json/PostgresqlJsonMapDomainIntegrationSpec.groovy
new file mode 100644
index 0000000..7fbf9d5
--- /dev/null
+++ b/test/integration/net/kaleidos/hibernate/json/PostgresqlJsonMapDomainIntegrationSpec.groovy
@@ -0,0 +1,41 @@
+package net.kaleidos.hibernate.json
+
+import spock.lang.Specification
+import spock.lang.Unroll
+import test.json.TestMapJson
+
+class PostgresqlJsonMapDomainIntegrationSpec extends Specification {
+
+    @Unroll
+    void 'save a domain class with a map #map to json'() {
+        setup:
+            def testMapJson = new TestMapJson(data: map)
+
+        when:
+            testMapJson.save(flush: true)
+
+        then:
+            testMapJson.hasErrors() == false
+            testMapJson.data == map
+
+        where:
+            map << [null, [:], [name: 'Ivan', age: 34]]
+    }
+
+    void 'save and read a domain class with json'() {
+        setup:
+            def value = [name: 'Ivan', age: 34, hasChilds: true, childs: [[name: 'Judith', age: 7], [name: 'Adriana', age: 4]]]
+            def testMapJson = new TestMapJson(data: value)
+
+        when:
+            testMapJson.save(flush: true)
+
+        then:
+            testMapJson.hasErrors() == false
+
+        and:
+            def obj = testMapJson.get(testMapJson.id)
+            obj.data.keySet().collect { it.toString() }.equals(['name', 'age', 'hasChilds', 'childs'])
+            obj.data.childs.size() == 2
+    }
+}
\ No newline at end of file