Try using the IsoDateTimeConverter
that comes with Json.Net:
var date = new DateTime(2014, 5, 6, 17, 24, 55, DateTimeKind.Local);
var obj = new { date = new DateTimeOffset(date) };
JsonSerializerSettings settings = new JsonSerializerSettings();
settings.Converters.Add(new IsoDateTimeConverter
{
DateTimeFormat = "yyyy-MM-ddTHH:mm:ssZ",
DateTimeStyles = DateTimeStyles.AdjustToUniversal
});
string json = JsonConvert.SerializeObject(obj, settings);
Console.WriteLine(json);
Output:
{"date":"2014-05-06T22:24:55Z"}