Hydrides are compounds in widespread use as reducing agents for the synthesis of metallic nanoparticles. Importantly, the formation of high yields of small noble metal nanoparticles with high crystallinity and monodisperse size distributions has been developed in part thanks to the use of such chemical species. In this Chapter we will give a broad overview on the use of hydrides as reducing agents for the synthesis of inorganic crystals with different chemical compositions (metals, ceramics, alloys), paying particular attention to the different applications derived.