Hi,

I have written some macro in VBA. It has 2 buttons one is SUBMIT and another is CANCEL. When i click on SUBMIT then it calls access and populate the data in another excel file and takes around 20-30 minutes to populate/complete the process. What I want is on click on CANCEL it should stop the process.

Any help will be appreciated.

Insert DoEvents in your loop. There are several ways to acutally accomplish this.
This is quick and dirty. Create 2 buttons and name them (Start_Button and Stop_Button).

Put this code in the click routines:
----------------------------------------------------------------------
Private Sub Start_Button_Click()

'Starts code
  Do While "" = ""
    Cells(1, 1).Value = "Started"
    DoEvents
  Loop

End Sub

Private Sub Stop_Button_Click()

'Stops code
  Cells(1, 1).Value = "Not Started"
  End

End Sub
----------------------------------------------------------------------

A clean halt should have your code stopping after processing the record it's on or you may not like the results. One way to do this is to set a value that the running routine can check. Then when the running code checks this value it would know to stop after finishing current record.