In this book recent developments in dehydrogenation reactions catalyzed by 3d-metals are discussed. With continue efforts to develop sustainable chemical production the discovery of new catalysts and catalytic procedures for (de)hydrogenation reactions are a subject of great interest to the chemistry community. Additionally, (de)hydrogenation reactions enable the creation of closed-loop production cycles that support a circular economy. The chapters presented include the synthesis of heterocycles and tandem-multicomponent (three or more) reactions through dehydrogenative strategy, as well as the conversion of ethanol to n-butanol, higher oxidized hydrocarbons like acids, ester, amides from alcohols, α-alkylation of amines, ketones, and amides with alcohols and mechanistic understanding of dehydrogenation reactions with high-valent metals. With contributions from experts in the field, the book is a valuable resource for scholars working in the field of organometallic chemistry, catalysis, medicinal chemistry, as well as researchers in the industry.