Perovskite-like oxides (i. e., LaSrNiO4) prepared by combustion method with various complexes and amounts are compared and their catalytic performances for CO oxidation are tested. Results indicate that sample prepared with oxalic acid as the complex and 100% in excess of cations shows the best and stable activity for oxidation reaction, suggesting that oxalic acid is a preferential complex in the synthesis of perovskite-like catalyst by combustion method.