Reactions of laser-ablated Al, Ga, In, and Tl atoms with H2O2 and with H-2 + O-2 mixtures diluted in argon give new absorptions in the O-H and M-O stretching and O-H bending regions, which are assigned to the metal mono-, di-, and trihydroxide molecules. Isotopic substitutions (D2O2, O-18(2), O-16,18(2), HD, and D-2) confirm the assignments, and DFT calculations reproduce the experimental results. Infrared spectra for the Al(OH)(OD) molecule verify the calculated C-2v structure. The trihydroxide molecules increase on annealing from the spontaneous reaction with a second H2O2 molecule. Aluminum atom reactions with the H-2 + O-2 mixtures favor the HAl(OH)(2) product, suggesting that AlH3 generated by UV irradiation combines with O-2 to form HAl(OH)(2).