Hi.
If you are processing via ajax when the button is clicked-
1. Disable the button when processing starts
2. Enable the button after processing completes
If the button postbacks, the best way is to disable the button when it is clicked via javascript [I won't suggest jquery just for this particular task]. Since after postback the button will be enabled as it was earlier, you don't need to worry about enabling.
<asp:Button ID="btn" runat="server" OnClientClick="disable(this)"
Text="Click me!" OnClick="btn_Click" />
<script type="text/javascript">
function disable(control)
{
control.disabled="disabled";
//added alert to give the snapshot of what happens
//when the button is clicked
alert(100);
}
</script>
Hope this helps.