A research and development program by Studebaker-Packard on catalytic converter system designs is discussed, along with details of specific problem areas encountered, methods used in their solution, and an outline of remaining unresolved problems. Data are presented which show the effect on conversion efficiency of catalyst bed configuration, catalyst temperature, auxiliary air, and gasoline additives. Catalyst warmup rate and more effective utilization of available exhaust heat is discussed. Performance of several catalysts under various automobile operating conditions are illustrated.