The effects of partial substitution of Mn by Cu and calcination temperature on the physiochemical and catalytic properties of La0.8K0.2CuxMn1-xO3 catalysts for the simultaneous removal of NOx and soot were investigated. The XRD, SEM, and BET techniques were used to characterize the catalysts, and temperature-programmed reaction (TPR) was used to determine their catalytic performances. The XRD results show that these catalysts are perovskite-type oxides. The SEM and BET results indicate that these catalysts exhibit very good characteristics for multiphase reactions. The TPR results demonstrate that the performances of the catalysts can be improved by doping with appropriate cations. With increasing catalyst calcination temperature, the ignition temperature of the soot increases. The catalyst La0.8K0.2Cu0.05Mn0.95O3 calcined at 750 degrees C was found to be the best among the catalysts tested. The maximum yield of NO to N-2 and the ignition temperature of soot were 54.8% and 260 degrees C, respectively, for this catalyst.