The development of new catalytic systems for cis-dihydroxylation and epoxidation of alkenes, based on atom economic and environmentally friendly concepts, is a major contemporary challenge. In recent years, several systems based on manganese catalysts using H₂O₂ as the terminal oxidant have been developed. In this review, selected homogeneous manganese catalytic systems, including ‘ligand free’ and pyridyl amineligand based systems, that have been applied to alkene oxidation will be discussed with a strong focus on the mechanistic studies that have been carried out.