An aged commercial three-way automotive catalyst was examined with respect to regeneration procedures. Catalyst samples were leached with acetic acid to remove contaminants accumulated on the catalyst surface during operation. The optimum leaching conditions concerning acetic acid concentration, solution feed rate and temperature were investigated. The leached samples were examined for their catalytic activity (CO and C2H4 oxidation, NO reduction and N-2 production) in comparison with samples of fresh and aged catalysts. The leaching procedure improves considerably the catalytic activity, where in the case of C2H4 oxidation, NO reduction reaches the activity of the fresh catalyst.