Compound of La 2−x Sr x CuO 4 (x≥0.5) with T * phase structure were prepared by conventional citric method. The split peak at 2θ=∼31° in XRD patterns and the broad absorption band at 680cm −1 with a shoulder peak at 620cm −1 in IR spectra suggested the formation of T * phase in La 2−x Sr x CuO 4 compounds at x≥0.5. The amount of sample with T * phase structure increased with the increase of Sr content as certified by XRD patterns. Catalytic performance of La 2−x Sr x CuO 4 for NO decomposition was investigated, and it was found, by correlating the solid-state properties and the activity of NO decomposition, that the presence of T * phase structure enhanced the catalytic activity of La 2−x Sr x CuO 4 in NO decomposition.