We have investigated the lowest triplet and singlet potential energy surfaces (PESs) for the reaction of Ga-2 dimer with water. Under thermal conditions, we predict formation of the triplet ground state addition complex (Ga2OH2)-O-center dot center dot center dot(B-3(1)) involving Ga center dot center dot center dot O center dot center dot center dot Ga bridge interaction. At the coupled cluster CCSD(T)/AE (CCSD(T)/ECP) computational levels, Ga-2 center dot center dot center dot OH2(B-3(1)) is bound by 5.5 (5.7) kcal/mol with respect to the ground state reactants Ga-2((3)Pi(u)) + H2O. Identification of the addition complex is in agreement with the experimental evidence from matrix isolation infrared (IR) spectroscopy reported recently by Macrae and Downs. The located minimum energy crossing points (MECPs) between the triplet and singlet energy surfaces on the entrance channel of Ga-2 + H2O are not expected to be energetically accessible under the matrix conditions, consistent with the lack of occurrence of Ga2 insertion into the O-H bond under such conditions. The computed energies and harmonic and anharmonic vibrational frequencies for the triplet and singlet Ga2(H)(OH) insertion isomers indicate the singlet double-bridged Ga(mu-H)(mu-OH)Ga isomer to be the most stable and support the experimental IR identification of this species. The energy barrier for elimination of H-2 from the second most stable singlet HGa(mu-OH)Ga insertion isomer found to be 13.9 (12.9) kcal/mol is also consistent with the available experimental data.