The evaluation of catalytic activity for Rh-Pd/YBa(Co 1−x M x) 4 O 7 /␥-Al 2 O 3 (M = Al, Ce, Zr, and La) showed that the efficiency of NO x reduction depends strongly on the nature of the OSMs. Among a series of oxygen storage materials, YBa(Co 1−x M x) 4 O 7 (M = Ce, Zr, La, Ga and In) studied for catalyst enhancement, only the catalyst with YBa(Co 0.9 Ce 0.1) 4 O 7 has better conversion efficiency respectively (85% of NO, 96% of CO and 92% of HC). After treatment at 1000 • C for 3 h, these fresh catalysts showed a substantial decrease of their catalytic activities, only Rh-Pd/YBa(Co 0.9 Ce 0.1) 4 O 7 /␥-Al 2 O 3 retains its high catalytic activity.