Here is a sample try this
<asp:GridView ID="GridView1" runat="server" AllowPaging="True"
AutoGenerateColumns="False" DataKeyNames="ProductID"
DataSourceID="SqlDataSource1" onrowdatabound="GridView1_RowDataBound">
<Columns>
<asp:BoundField DataField="ProductID" HeaderText="ProductID"
InsertVisible="False" ReadOnly="True" SortExpression="ProductID" />
<asp:BoundField DataField="ProductName" HeaderText="ProductName"
SortExpression="ProductName" />
<asp:TemplateField HeaderText="del">
<ItemTemplate>
<asp:Button ID="Button1" runat="server" onclick="Button1_Click" Text="Button" />
</ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>
Code behind
protected void Button1_Click(object sender, EventArgs e)
{
Button btn = (Button)sender;
GridViewRow gvr = (GridViewRow)btn.NamingContainer;
int index = gvr.RowIndex;
string value = GridView1.Rows[index].Cells[1].Text;
}