We employ state-selective triple-resonance vibrational overtone spectroscopy for a direct measurement of the lowest dissociation energy, Do, in the (H2O)-O-18 molecule. The measured value of 41 154.22 +/- 0.25 cm(-1) is in an excellent agreement with that, predicted by ab initio theoretical calculations. This result validates the computations, adding more confidence to what this theory can predict for water. In addition, we have measured the required for this experiment energy levels of (H2O)-O-18 in the region near 27 000 cm(-1), as well as the laser-induced fluorescence (LIF) spectrum of the (OH)-O-18 isotopologue, for which near 60 electronic transitions have been assigned. (C) 2015 Elsevier B.V. All rights reserved.