suribabuk

k its fine but the data is coming through database its not a bound fiels or custom field

I suppose, u have set autogeneratecolumns to true for gridview... so u dont have columns defined using boundcolumn or templatecolumn...

u can create RowDataBound event of gridview (select gridview and go to properties window... navigate to event section and doubleclick on RowDataBound event)

define event as this

protected void GridView1_RowDataBound(object sender, System.Web.UI.WebControls.GridViewRowEventArgs e)
{
	if(e.Row.RowType == DataControlRowType.DataRow)
         {
		e.Row.Cells[1].Text = Strings.Format(Convert.ToDecimal(e.Row.Cells[1].Text), "#,##0.00");
	}
}

considering second column (index 1) need to be formatted i have used Cells[1] in above code... replace index value based on column sequence number 

hope this helps...