Phosphoranimide-metal catalysts and their role in hydrodesulfurization and hydrogenation are disclosed. The catalysts comprise of first row transition metals such as nickel, cobalt and iron. The catalysts have a metal to anionic phosphoranimide ratio of 1:1 and have no inactive bulk phase and no dative ancillary ligands. In one embodiment, the catalysts comprise discrete mixed-valent precatalyst clusters, the electronic state of which can be adjusted to optimize catalytic activity. The catalysts catalyze the hydrodesulfurization of a range of sulfur-containing organic compounds under lower temperature and pressure conditions than those conditions commonly used in industrial hydrodesulfurization. The catalysts also catalyze the hydrogenation of substrates comprising at least one carbon-carbon double bond which is not present in an aromatic moiety, although the substrate itself may include an aromatic moiety.