The purpose of this chapter is to present the results of an experimental study of the performance and conversion efficiencies of ceramic monolith three-way catalytic converters (TWCC) employed in automotive exhaust lines for the reduction of gasoline emissions. Two ceramic converters of different cell density, substrate length, hydraulic channel diameter and \vall thickness were studied to investigate the effect of varying key parameters on conversion efficiencies and pressure drop. Based on the emission test results, the conversion efficiencies of
HC from both converters were calculated and evaluated
