To comply with increasingly stringent emission regulations, there is a high demand for A/F sensors with shorter light-off time and higher accuracy. Improvement of sensor accuracy requires reduction in sensor output shift induced by unburned hydrogen in the exhaust gas. The sensor output shift can effectively be reduced by placing a catalyst at the gas inlet of the sensing element. However, this involves the challenging technical task of developing a catalyst material with high durability in the sensor operating environment. By using a theoretical analysis technique, we studied a new catalyst material with superior catalytic performance and high durability, and have successfully improved A/F sensor accuracy, as reported in the following paper.