diff --git a/Code/Mantid/MantidQt/MantidWidgets/inc/MantidQtMantidWidgets/MuonSequentialFitDialog.h b/Code/Mantid/MantidQt/MantidWidgets/inc/MantidQtMantidWidgets/MuonSequentialFitDialog.h
index e920d1c7be39..3c188706d007 100644
--- a/Code/Mantid/MantidQt/MantidWidgets/inc/MantidQtMantidWidgets/MuonSequentialFitDialog.h
+++ b/Code/Mantid/MantidQt/MantidWidgets/inc/MantidQtMantidWidgets/MuonSequentialFitDialog.h
@@ -45,11 +45,19 @@ namespace MantidWidgets
     virtual ~MuonSequentialFitDialog();
 
   private:
+    enum ControlButtonType {
+      Start,
+      Stop
+    };
+
     // -- FUNCTIONS -----------------------------------------------------------
 
     /// Check if all the input field are valid 
     bool isInputValid();
 
+    /// Set the type of the control button
+    void setControlButtonType(ControlButtonType type);
+
     // -- VARIABLES -----------------------------------------------------------
 
     /// UI form
@@ -70,6 +78,11 @@ namespace MantidWidgets
     /// Enables/disables start button depending on wether we are allowed to start
     void updateControlButtonState();
 
+    /// Start fitting process
+    void startFit();
+
+    /// Stop fitting process
+    void stopFit();
   };
 
 
diff --git a/Code/Mantid/MantidQt/MantidWidgets/src/MuonSequentialFitDialog.cpp b/Code/Mantid/MantidQt/MantidWidgets/src/MuonSequentialFitDialog.cpp
index 24e44434d944..ed86f79038c8 100644
--- a/Code/Mantid/MantidQt/MantidWidgets/src/MuonSequentialFitDialog.cpp
+++ b/Code/Mantid/MantidQt/MantidWidgets/src/MuonSequentialFitDialog.cpp
@@ -14,11 +14,12 @@ namespace MantidWidgets
    * Constructor
    */
   MuonSequentialFitDialog::MuonSequentialFitDialog(QWidget* parent) :
-    QDialog(parent) 
+    QDialog(parent)
   {
     m_ui.setupUi(this);
 
     // TODO: set initial values 
+    setControlButtonType(Start); 
 
     // After initial values are set, update depending elements accordingly. We don't rely on
     // slot/signal update, as element might be left with default values which means these will
@@ -84,6 +85,43 @@ namespace MantidWidgets
     m_ui.controlButton->setEnabled( isInputValid() );
   }
 
+  /**
+   * Set the type of the control button. It is Start button when fitting has not been started,
+   * and Stop button when fitting is running.
+   * @param type :: New type of the button  
+   */
+  void MuonSequentialFitDialog::setControlButtonType(ControlButtonType type)
+  {
+    // Disconnect everything connected to pressed() signal of the button 
+    disconnect( m_ui.controlButton, SIGNAL( pressed() ), 0, 0);
+ 
+    // Connect to appropriate slot
+    auto buttonSlot = (type == Start) ? SLOT( startFit() ) : SLOT( stopFit() );
+    connect( m_ui.controlButton, SIGNAL( pressed() ), this, buttonSlot );
+
+    // Set appropriate text
+    QString buttonText = (type == Start) ? "Start" : "Stop";
+    m_ui.controlButton->setText(buttonText);
+  }
+
+  /**
+   * Start fitting process.
+   */
+  void MuonSequentialFitDialog::startFit()
+  {
+    g_log.notice("Seq. fitting started");
+    setControlButtonType(Stop);
+  }
+
+  /**
+   * Stop fitting process.
+   */
+  void MuonSequentialFitDialog::stopFit()
+  {
+    g_log.notice("Seq. fitting stopped");
+    setControlButtonType(Start);
+  }
+
   /**
    * Destructor
    */