Parse string in HH.mm format to TimeSpan

string YourString = "01.35";

var hours = Int32.Parse(YourString.Split('.')[0]);
var minutes = Int32.Parse(YourString.Split('.')[1]);

var ts = new TimeSpan(hours, minutes, 0);

Updated answer:

Unfortunately .NET 3 does not allow custom TimeSpan formats to be used, so you are left with doing something manually. I 'd just do the replace as you suggest.

Original answer (applies to .NET 4+ only):

Use TimeSpan.ParseExact, specifying a custom format string:

var timeSpan = TimeSpan.ParseExact("11.35", "mm'.'ss", null);

Parse out the DateTime and use its TimeOfDay property which is a TimeSpan structure:

string s = "17.34";
var ts = DateTime.ParseExact(s, "HH.mm", CultureInfo.InvariantCulture).TimeOfDay;