Hi,
<form id="form1" runat="server">
<div>
<asp:ScriptManager ID="ToolkitScriptManager1" runat="server">
</asp:ScriptManager>
<asp:Accordion
ID="Accordion1"
CssClass="accordion"
HeaderCssClass="accordionHeader"
HeaderSelectedCssClass="accordionHeaderSelected"
ContentCssClass="accordionContent"
runat="server">
<contenttemplate>
<asp:gridview id="grd1" runat="server" xmlns:asp="#unknown"></asp:gridview>
</contenttemplate>
</asp:Accordion>
</div></form>
</form>
Please follow the above sample code.