The reduction of the mononitrosyl Re(II) salt [NMe₄]₂[ReCl₅(NO)] (1) with zinc in acetonitrile afforded the Re(I) dichloride complex [ReCl₂(NO)(CH₃CN)₃] (2). Subsequent ligand substitution reactions with PCy₃, PiPr₃ and P(p-tolyl)₃ afforded the bisphosphine Re(I) complexes [ReCl₂(NO)(PR₃)₂(CH₃CN)] (3, R = Cy a, iPr b, p-tolyl c) in good yields. The acetonitrile ligand in 3 is labile, permitting its replacement with H₂ (1 bar) to afford the dihydrogen Re(I) complexes [ReCl₂(NO)(PR₃)₂(η²-H₂)] (4, R = Cy a, iPr b). The catalytic activity of 2, 3 and 4 in hydrogen-related catalyses including dehydrocoupling of Me₂NH·BH₃, dehydrogenative silylation of styrenes, and hydrosilylation of ketones and aryl aldehydes were investigated, with the main focus on phosphine and halide effects. In the dehydrocoupling of Me₂NH·BH₃, the phosphine-free complex 2 exhibits the same activity as the bisphosphine-substituted systems. In the dehydrogenative silylation of styrenes, 3a and 4a bearing PCy₃ ligands exhibit high catalytic activities. Monochloro Re(I) hydrides [Re(Cl)(H)(NO)(PR₃)₂(CH₃CN)] (5, R = Cy a, iPr b) were proven to be formed in the initiation pathway. The phosphine-free complex 2 showed in dehydrogenative silylations even higher activity than the bisphosphine derivatives, which further emphasizes the importance of a facile phosphine dissociation in the catalytic process. In the hydrosilylation of ketones and aryl aldehydes, at least one rhenium-bound phosphine is required to ensure high catalytic activity.