Manganese is a first-row transition metal that serves as a versatile catalyst in oxidation and hydrogenation chemistry. It exhibits multiple oxidation states, primarily Mn(II), Mn(III), and Mn(VII), which enable diverse catalytic cycles. Manganese-based catalysts are prominent in selective oxidations, such as the epoxidation of olefins, alcohol oxidation, and C–H bond functionalization, often inspired by manganese-containing enzymes like manganese catalase and manganese peroxidase. Manganese salen complexes are well-known for asymmetric epoxidations, achieving high enantioselectivity. In hydrogenation, manganese pincer complexes have gained attention as earth-abundant alternatives to noble metal catalysts for the hydrogenation of ketones, nitriles, and esters under mild conditions. The development of manganese catalysis aligns with green chemistry principles, emphasizing sustainability and low toxicity. Additionally, manganese catalysts participate in photoredox processes and radical reactions, broadening their synthetic utility.