Please check out this..
I tried it..working fine..
<script language="javascript" type="text/javascript">
function disablethis()
{
document.getElementById("LinkButton1").disabled = true;
}
</script>
calling the javascript function
disablethis()
on event
onClientClick
of linkbutton
<asp:linkbutton id="LinkButton1" runat="server" onclientclick="javascript:return disablethis()" xmlns:asp="#unknown">LinkButton</asp:linkbutton>
Mark it solution if you got your answer.
Thanks