Disclosed herein, among other things, are methods and apparatus related to radio frequency (RF) ablation catheters. The present subject matter provides a method for forming an ablation catheter having a balloon at a distal end of the catheter. The method includes applying a band of conductive material to an outer surface of the balloon. The band of conductive material is adapted to provide one or more electrodes for radio frequency ablation therapy. A distal end of a lead is connected to the band of conductive material. The balloon is inverted, so that the inverted balloon includes the band of conductive material on an inside surface. According to various embodiments, the balloon includes a semi-permeable or hydro-able membrane.