This paper presents an extensive temperature dependent kinetic study of the catalytic HOx ozone cycle, (1) OH + O3 → HO2 + O2 and (2) HO2 + O3 → OH + 2 O2, based on time-resolved, Doppler limited direct absorption spectroscopy of OH with a single mode (Δν = 0.0001 cm-1) high-resolution infrared laser. The sum of the two chain rate constants, k1 + k2, is measured over the 190−315 K temperature range and can be accurately described by an Arrhenius-type expression: k1 + k2 (cm3/s) = 2.26(40) × 10-12 exp[−976(50)/T]. These results are in excellent agreement with studies by Ravishankara et al. [J. Chem. Phys. 1979, 70, 984] and Smith et al. [Int. J. Chem. Kinet. 1984, 16, 41] but are significantly higher than the values currently accepted for atmospheric modeling. In addition, these studies also reflect the first such rate measurements to access the 190−230 K temperature range relevant to kinetic modeling of ozone chain loss in the lower stratosphere.