We have performed a direct measurement of one of the most fundamental thermochemical values: the O-H bond energy in water. Using a triple-resonance laser excitation scheme, we excite the molecule through a series of vibrational overtone transitions to access directly the onset of the dissociative continuum. The disociation energy obtained from our experiments, 41145.94±0.15 cm-1, is ~30 times more accurate than the currently accepted value and has important implications for other thermochemical quantities linked to the bond energy of water.