SCF and Møller–Plesset calculations were done for the hydrated alkaline-earth ions in the gas phase. The systems studied were M2+(H2O)n, where M = Mg, Ca, and Sr, and n = 1,2,3,4, and 6. The successive ion–water bond energies were in the range anticipated on the basis of extrapolation of results from experimental studies on larger hydrates. Keywords: hydrates, alkaline-earth cations, quantum-chemical calculations.