Involved in the maturation of [NiFe] hydrogenases. Involved in the biosynthesis of the Fe(CN)(2)CO cofactor (PubMed:15504408, PubMed:23022438). HypC delivers iron-bound CO(2) to HypD where reduction to CO probably occurs (PubMed:23851071). In complex with HypD, accepts the cyanide ligand generated by HypF and HypE, and also coordinates the carbon monoxide ligand (PubMed:15504408, PubMed:23022438). Involved in the maturation of the hydrogenase 3 (PubMed:10783387, PubMed:11292801). Also participates in the maturation of hydrogenase 1 (PubMed:11292801). Protein modification; [NiFe] hydrogenase maturation. Homodimer (PubMed:9485446). Interacts with HypD (PubMed:12441107, PubMed:15504408, PubMed:23022438). Also forms a complex with HypD and HypE (PubMed:15504408). Interacts with the precursor form of HycE (pre-HycE), the large subunit of hydrogenase 3 (PubMed:9485446, PubMed:10783387, PubMed:12441107). Deletion of both hybG and hypC completely abolishes hydrogenase activity. Belongs to the HupF/HypC family.