Response.Clear();
Response.AddHeader("content-disposition", "attachment;filename=Export.xls");
Response.Charset = "";
Response.Cache.SetCacheability(HttpCacheability.NoCache);
Response.ContentType = "application/vnd.xls";
StringWriter stringWrite = new StringWriter();
HtmlTextWriter htmlWrite = new HtmlTextWriter(stringWrite);
GridView grid = new GridView();
grid.DataSource = SomeObject.GetSome();
grid.DataBind();
grid.RenderControl(htmlWrite);
Response.Write(stringWrite.ToString());
Response.End();