The equilibrium geometries, vibrational frequencies and isomerism of MOH (M = Be and Mg) have been investigated at the B3PW91 level using two basis sets, 6-31G* and 6-311 +G(2d,2p). The calculated geometries, vibrational frequencies and zero-point vibrational energies are in good agreement with the CASSCF level studies of Kong and Boyd. The isomerization products of BeOH and MgOH are structurally similar. The M-O bond length in HMO (M = Be and Mg) is predicted to be longer than that in the corresponding MOH. The predicted reaction energies for the reactions MOH --> HMO are endothermic and in good agreement with the CASSCF level results. The predicted ESR hyperfine coupling constants for MgOH and the dissociation energies for both BeOH and MgOH compare quite well with experimental results.