We report rate coefficients at 293 K for the collisional relaxation of H2O molecules from the highly excited parallel to04>(+/-) vibrational states in collisions with H2O, Ar, H-2, N-2, and O-2. In our experiments, the parallel to04>(-) state is populated by direct absorption of radiation from a pulsed dye laser tuned to similar to719 nm. Evolution of the population in the (parallel to04>(+/-)) levels is observed using the combination of a frequency-quadrupled Nd:YAG laser, which selectively photolyses H2O(parallel to04>(+/-)), and a frequency-doubled dye laser, which observes the OH(v=0) produced by photodissociation via laser-induced fluorescence. The delay between the pulse from the pump laser and those from the photolysis and probe lasers was systematically varied to generate kinetic decays. The rate coefficients for relaxation of H2O(parallel to04>(+/-)) obtained from these experiments, in units of cm3 molecule-1 s-1, are: k(H2O)=(4.1+/-1.2)x10(-10), k(Ar)=(4.9+/-1.1)x10(-12), k(H-2)=(6.8+/-1.1)x10(-12), k(N-2)=(7.7+/-1.5)x10(-12), k(O-2)=(6.7+/-1.4)x10(-12). The implications of these results for our previous reports of rate constants for the removal of H2O molecules in selected vibrational states by collisions with H atoms (P. W. Barnes , Faraday Discuss. Chem. Soc. 113, 167 (1999) and P. W. Barnes , J. Chem. Phys. 115, 4586 (2001).) are fully discussed. (C) 2004 American Institute of Physics.