Abstract: A cation exchange membrane includes a film of fluorinated ionomer containing sulfonate groups. The film has a machine direction and a transverse direction perpendicular to the machine direction. The membrane has a water swell in both the machine direction and the transverse direction of less than about 5%. The membrane has a ratio of in-plane conductivity in the machine direction to in-plane conductivity in the transverse direction of about 0.9 to about 1.1. A process makes a cation exchange membrane including a film of fluorinated ionomer containing sulfonate groups. The process includes forming a film of the ionomer. The process also includes biaxially stretching the film in both a machine direction and a transverse direction perpendicular to the machine direction. An electrochemical cell has anode and cathode compartments and includes a cation exchange membrane as a separator between the anode and cathode compartments.