The results of a development program for Pd-only and Pd/Rh automotive emission control catalysts are discussed. A review of former experiences with Pd-containing systems, especially their poor tolerance against lead and sulfur poisoning is given. Model gas experiments were conducted with improved Pd-based catalysts. Not only the activity to convert simultaneously CO, NOx and hydrocarbons (HC) was investigated, but also the formation of so-called secondary emissions such as N20 or N H 3. The catalyst development was supported by XPS-measurements paying special attention to the oxidation state, spread and the dispersion of Pd. Promising Pd and Pd/Rh-catalyst candidates were tested fresh and after engine aging on engine- and vehicle dynamometers. The results are compared to Pt/Rh-catalysts. For Pd-only catalysts the ratio of catalyst volume to vehicle mass seems to be one important factor to guarantee high conversion levels after aging. The Pd/Rh-technologies reported in this study showed similar activities on different vehicles and in different test cycles as Pt/Rh catalysts. With the new developed Pd/Rh-catalyst the European legislation for model year 1996 could be achieved thus representing an economical and technical alternative to Pt/Rh-catalysts. Major potential for further improving the Pd/Rhtechnologies performance must be seen in an optimization work regarding fuel quality and A/F-management.