Alumina-supported Fe and Ce catalysts with carburization treatment were prepared to investigate their performance for auto emission control. The carburization treatment in flowing CO at 525 degrees C significantly promoted the catalytic activity of C/Fe-Ce, even comparable to a noble metal catalyst 1.0 wt % Pt/CeO2. The XRD result suggests that the formation of Fe3C is a possible interpretation for the promoted activity by the carburization treatment. The T50 contour lines of NOx and CO were used to quickly optimize catalyst composition, and C/18Fe-18Ce-64Alumina was considered to be the optimization result.