namespace MyService { [ServiceContract(Namespace = "")] [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)] public class MyAjaxService { [OperationContract] public double Sum(double a, double b) { double result = a + b; return result; } } } $(document).ready(function() { $("#btn").click(function() { var num1 = $("#txt1").val(); var num2 = $("#txt2").val(); $.ajax({ url: "MyAJAXService.svc/Sum", type: "POST", contentType: "application/json; charset=utf-8", data: JSON.stringify({ a: num1, b: num2 }), dataType: "json", success: function(data) { $("#txt3").val(data.d); }, error: function(err) { alert(err); } }); }); }); <%@ Page Title="Home Page" Language="C#" MasterPageFile="~/Site.Master" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="MyService._Default" %> <asp:Content ID="BodyContent" ContentPlaceHolderID="MainContent" runat="server"> <input id="txt1" type="text" /><br /> <br /> <input id="txt2" type="text" /><br /> <br /> <input id="btn" type="button" value="Add Numbers" /><br /> <br /> <input id="txt3" type="text" /> </asp:Content>