Try this…
var test = "2015-05-08T05:00Z";
DateTime testTime = new DateTime();
testTime = DateTime.Parse(test, null, System.Globalization.DateTimeStyles.RoundtripKind);
Console.WriteLine(testTime);
Console.ReadLine();
Or even with DateTime.ParseExact()
var test = "2015-05-08T05:00Z";
DateTime testTime = new DateTime();
testTime = DateTime.ParseExact(test, "yyyy-MM-ddTHH:ssZ", System.Globalization.CultureInfo.InvariantCulture, DateTimeStyles.RoundtripKind);
Console.WriteLine(testTime);
Console.ReadLine();
Results:
1
solved Converting string to valid DateTime