Traces of CO in hydrogen rich gas streams poison the anode of proton exchange membrane fuel cells reducing their power output and decreasing the cell life. This paper investigates the CO selective oxidation in simulated reformate gas by using catalytic zeolite membranes. In particular, the CO removal efficiency was explored using catalytic membranes characterized by different permeation properties (prepared using different protocols) and loaded with the catalyst by means of cationic exchange and reduction process. The most promising experimental results are obtained with membranes prepared with small crystals and low concentration of zeolite suspension (during the seeding step) and with a hydrothermal treatment of 90 degrees C for 24 h. These membranes are characterized by lower permeance and showed interesting catalytic performance in terms of CO reduction and selectivity.