Refer this.
You can remove the Button tag and have the ASP Button if you want it will work.
Replace Button with
<asp:Button ID="btnMouseOver" Text="Mouse Over" runat="server" />
HTML
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
<script src="http://ajax.aspnetcdn.com/ajax/jQuery/jquery-1.11.1.min.js"></script>
<script type="text/javascript">
$(document).ready(function () {
$("[id*=btnMouseOver]").mouseover(function () {
alert('This is MouseOver on Button');
});
});
</script>
</head>
<body>
<form id="form1" runat="server">
<div>
<button id="btnMouseOver" value="MouseOver">
Mouse Over
</button>
</div>
</form>
</body>
</html>
Demo