The rate coefficient for the reaction O(3p) + OClO has been measured at low pressure (1-5 Torr) over the temperature range 200400 K. The experiments were performed in a discharge flow system with atomic resonance fluorescence detection of O(3P). The ratio of [OClO]/[O] was kept very high (usually 10(3)-10(4)) in order to avoid secondary reactions. At 298 K, k = (1.0 +/- 0.3) X 10(-13) molecules-1 cm3 s-1, which is consistent with recent results obtained at high pressure (8-800 Torr argon) and extrapolated to zero pressure. In the present low-pressure experiments, the rate coefficient increases with increasing temperature from 243 to 400 K while from 200 to 225 K the rate coefficient decreases with increasing temperature. The Arrhenius expression for the 243-400 K region is k = (2.4 +/- 0.8) X 10(-12) exp[(-960 +/- 120)/T] molecule-1 cm3 s-1. The trend observed here for T = 243-400 K is opposite to that inferred from the extrapolation of high-pressure results (20-600 Torr argon) at T = 248-312 K. Our high-temperature results (243-400 K) are consistent with the bimolecular abstraction channel, O(3P) + OClO --> ClO + O2.