using System;

using System.Collections.Generic;

using Newtonsoft.Json;

public class Program

{

    public static void Main()

    {

        var testJson = "{\"data\":{\"11\": \"test11\"}}";

        var deserialized = (TestClass) JsonConvert.DeserializeObject(testJson, typeof(TestClass));

        Console.WriteLine(deserialized.Data[11]);

    }

}

public class TestClass

{

    public Dictionary<int, string> Data {get;set;}

}

​