Abstract: The catalysts used for manufacturing methyl methacrylate (MMA) by two-step conversion of isobutylene via methacrolein (MAL) were studied. The selective oxidation of isobutylene to MAL was carried out in a fixed-bed flow microreactor using a series of Mo-Bi-containing catalysts and the oxidative esterification of MAL to MMA was carried out in a slurry-bed reactor using a series of palladium-containing catalysts.By means of BET and XPS, the properties of the catalysts were characterized.It was found that the performance of Mo-Bi-Co-Fe-Ce-O catalyst was improved distinctly when Cs was added for the selective oxidation of isobutylene to MAL, and the Pd₅Bi₂PbFe/CaCO₃ catalyst with the loading sequence of Pd, Pb and Bi, Fe showed the best performance for the oxidative esterification of MAL to MMA.