The gas phase reaction of HO2 radials with NO was studied using a discharge-flow system and laser-magnetic resonance detection. Concentrations of HO2 down to 2¿109 molecules/cm3 were detectable, thus allowing the reaction to be studied under pseudo-first-order kinetic conditions. The rate constant was measured using three independent kinetic schemes, one of which involved the detection of the reaction products OH and NO2. The three schemes gave results in excellent agreement. The rate constant, k1, for the reaction HO2+NO→OH+NO2 is (8.1¿1.5) ¿10-12 cm3/molecule⋅s at 296K and a pressure of 140--220 Pa (1.1--1.7 torr). The measurements also indicate that the rate constants for two other exothermic channels of the reaction are less than 2% of k1.