The type of O species in perovskite-type oxides LaMnyCo1-yO3(y = 0.0, 0.1, 0.3, 0.5, 0.7, 0.9, 1.0) was studied by XRD, XPS and TPD. The catalytic activity in NH3 oxidation was also studied. There were 3 desorption peaks in TPD curve corresponding to 3 types of O species (a, b, b'). The desorption temps. were 293 K ?Ta ?773 K, 773 K ?Tb ?1073 K and Tb' ?1073 K, resp. The relation among the composition, structure and the catalytic property of the catlyst was correlated and could be explained with a model based on solid defect reaction and the interaction between Co and Mn ions. The adsorption strength and quantity of a O are proportional to the catalytic activity. The synergetic effect between B-site ions seems to the benefit of the NH3 oxidation reaction.

Key words: CRYSTAL STRUCTURE DETERMINATION, OXIDATION, CATALYST, X-RAY DIFFRACTION ANALYSIS, SPECIFIC SURFACE AREA, MANGANESE OXIDE, COBALT OXIDE, STRUCTURE AND PROPERTY CORRELATION, DOUBLE OXIDE, PEROVSKITE TYPE STRUCTURE