The photolysis of ozone in 40 Torr nitrogen with small amounts of water was used to measure the O + OH rate constant at 295 K. A value of 3.17 +/- 0.51(1sigma) x 10(-11) cm(3)/s was determined by kinetic modeling of OH decays monitored by laser induced fluorescence, in agreement with current recommendations. (C) 2002 Published by Elsevier Science B.V.