Hydrometalation of alkenes with transition-metal hydrides (M-H) represents an important step in transition-metal-catalyzed transformations. Most of the reactions proceeded in anti-Markovnikov fashion to afford the corresponding adducts with high regioselectivity. On the other hand, the different types of reactions of alkenes with transition-metal hydrides, such as Co-H, Mn-H, and Fe-H, have been developed, which gave the corresponding organic radical species. Recently, a number of transformation reactions of the organic radical species catalyzed by transition-metal hydride complexes have been reported. Herein, the formation of organic radical species by the reaction of transition-metal hydrides with alkenes and their recent application to practical organic synthesis are highlighted.