I was trying to add items to IList through reflection, but while calling the \"Add\" method an error was thrown \"object ref. not set\". While debugging I came to know that
You're trying to find an Add method in Type, not in List - and then you're trying to invoke it on a Type.
MakeGenericType returns a type, not an instance of that type. If you want to create an instance, Activator.CreateInstance is usually the way to go. Try this:
Type objTyp = typeof(MyObject); //HardCoded TypeName for demo purpose
var IListRef = typeof (List<>);
Type[] IListParam = {objTyp};
object Result = Activator.CreateInstance(IListRef.MakeGenericType(IListParam));
MyObject objTemp = new MyObject();
Result.GetType().GetMethod("Add").Invoke(Result, new[] {objTemp });
(I would also suggest that you start following conventions for variable names, but that's a separate matter.)