in your aspx
<asp:repeater id="Repeater1" runat="server" onitemcommand="Repeater1_ItemCommand">
<itemtemplate>
<asp:button id="btnDetails" runat="server" text="Details" cssclass="aspxcontrolbuttons" commandname="Details" commandargument="<%# Eval("SomeValue") %>"></asp:button>
</itemtemplate>
</asp:repeater>
in your .cs
public void Repeater1_ItemCommand(Object Sender, RepeaterCommandEventArgs e)
{
if (e.CommandName == "Details")
{
string ID = (string)e.CommandArgument;
}
}