using System;

using System.Collections.Generic;

using System.Globalization;

using System.Linq;

using Newtonsoft.Json;

using Newtonsoft.Json.Converters;

public class Program

{

    public static void Main()

    {

        var jsonSettings = new JsonSerializerSettings

        {

            NullValueHandling = NullValueHandling.Ignore,

            DateFormatHandling = DateFormatHandling.IsoDateFormat

        };

​

        jsonSettings.Converters.Add(new IsoDateTimeConverter { DateTimeFormat = "yyyy-MM-ddTHH:mm:ss.fffZ" });

        var teste = new Teste

        {

            DtTeste = DateTime.Now

        };

        var conteudoJson = JsonConvert.SerializeObject(teste, Formatting.None, jsonSettings);

        Console.WriteLine(conteudoJson.ToString());

    }

    public class Teste

    {

        public DateTime DtTeste {get;set;}

    }

}