This review mainly discusses the application of oxido-peroxido Molybdenum(VI) complexes as catalysts or mediators in homogeneous or heterogeneous catalytic systems for oxidations of olefins, sulfides, alcohols, alkanes, and amines toward the synthesis of a variety of organic compounds, such as epoxides, sulfoxides, aldehydes and ketones, carboxylic acids, alcohols and nitroso compounds. (C) 2012 Elsevier B.V. All rights reserved.