Laser-ablated zinc and cadmium atoms were mixed uniformly with H-2 and O-2 in excess argon or neon and with 02 in pure hydrogen or deuterium during deposition at 8 or 4 K. UV irradiation excites metal atoms to insert into O-2 producing OMO molecules (M = Zn, Cd), which react further with H-2 to give the metal hydroxides M(OH)(2) and HMOH. The M(OH)(2) molecules were identified through O-H and M-O stretching modes with appropriate HD, D-2, O-16,18(2), and O-18(2) isotopic shifts. The HMOH molecules were characterized by O-H, M-H, and M-O stretching modes and an M-O-H bending mode, which were particularly strong in pure H-2/D-2. Analogous Zn and Cd atom reactions with H2O2 in excess argon produced the same M(OH)2 absorptions. Density functional theory and MP2 calculations reproduce the IR spectra of these molecules. The bonding of Group 12 metal dihydroxides and comparison to Group 2 dihydroxides are discussed. Although the Group 12 dihydroxide O-H stretching frequencies are lower, calculated charges show that the Group 2 dihydroxide molecules are more ionic.