Addition of La, Ba and Cc to Pd 3-way exhaust catalysts has been studied. The effect of these additives and temperature of calcination were studied on the activity of the catalysts stabilized in a simulated exhaust gas at 570 degrees C (1 h), using an experimental design. The catalytic activities were measured in the simulated exhaust gas as a function of temperature. Also, the activity of the catalysts for the NO - CO - O-2 system, was measured while changing the oxygen content. The results show that La promotes the reduction of NO at temperatures below 250 degrees C. Improved catalysts have a high thermal stability.