C# JSON.net – Serialize C# Object to JSON Issue

That's because Point has defined its own TypeConverter and JSON.NET uses it to do the serialization. I'm not sure whether there is a clean way to turn this behavior off, but you can certainly create your own JsonConverter that behaves the way you want:

class PointConverter : JsonConverter
{
    public override void WriteJson(
        JsonWriter writer, object value, JsonSerializer serializer)
    {
        var point = (Point)value;

        serializer.Serialize(
            writer, new JObject { { "X", point.X }, { "Y", point.Y } });
    }

    public override object ReadJson(
        JsonReader reader, Type objectType, object existingValue,
        JsonSerializer serializer)
    {
        var jObject = serializer.Deserialize<JObject>(reader);

        return new Point((int)jObject["X"], (int)jObject["Y"]);
    }

    public override bool CanConvert(Type objectType)
    {
        return objectType == typeof(Point);
    }
}

You can then use it like this:

JsonConvert.SerializeObject(
    new { Point = new Point(15, 12) },
    new PointConverter())

If you have a JObject, or a JArray containing JObjects, you can simply call ToString() on the JObject (or JArray) to get the JSON string. For example:

JObject jo = new JObject();
jo.Add("foo", "bar");
jo.Add("fizz", "buzz");

JObject jo2 = new JObject();
jo2.Add("foo", "baz");
jo2.Add("fizz", "bang");

JArray ja = new JArray();
ja.Add(jo);
ja.Add(jo2);

string json = ja.ToString();
Console.WriteLine(json);

Resulting JSON output:

[
  {
    "foo": "bar",
    "fizz": "buzz"
  },
  {
    "foo": "baz",
    "fizz": "bang"
  }
]

If you have a regular array of JObjects, you can pass it to JsonConvert.SerializeObject():

JObject[] arrayOfJObjects = new JObject[] { jo, jo2 };
json = JsonConvert.SerializeObject(arrayOfJObjects, Formatting.Indented);
Console.WriteLine(json);

This gives exactly the same JSON output as shown above.

JsonConvert.SerializeObject() also works fine on a single JObject:

json = JsonConvert.SerializeObject(jo, Formatting.Indented);
Console.WriteLine(json);

Output:

{
  "foo": "bar",
  "fizz": "buzz"
}

EDIT

I just noticed the ASP.NET MVC tag on your question.

If you're inside an MVC controller method then presumably you are doing something like this:

return Json(arrayOfJObjects);

which will not work. This is because MVC uses the JavaScriptSerializer, which does not know about Json.Net JObjects. What you need to do in this case is create your JSON using one of the methods I listed above, then return it from your controller method using the Content method like this:

string json = JsonConvert.SerializeObject(arrayOfJObjects);

return Content(json, "application/json");