using System;

using Newtonsoft.Json;

public class Program

{

    public static void Main()

    {

        var baseObj = new BaseClass() { MyProperty = "Base" };

        Console.WriteLine(JsonConvert.SerializeObject(baseObj));

        var childObj = new ChildClass() { MyProperty = "Child" };

        Console.WriteLine(JsonConvert.SerializeObject(childObj));

    }

}

​

public class BaseClass

{

    public virtual string MyProperty {get;set;} 

}

​

public class ChildClass : BaseClass

{

    [JsonIgnore]

    public override string MyProperty {get;set;}

}

​