We have measured the rate constants for the reaction of O+ ions with NO from room temperature to 1400 K. The reaction is slow (k = 8 X 10(-13) cm(3) s(-1)) at room temperature and the rate constant increases to 2.6 X 10(-12) cm(3) s(-1) at 1400 K. Comparison of the high-temperature data to drift tube data shows that rotational and translational energy are equally effective at controlling the rate constant, and that vibrational energy has at most a small effect on reactivity. Analysis of the data shows that the reaction proceeds by three different mechanisms. At the very low temperatures, we find a complex formation mechanism, and at the medium temperature range the behavior is interpreted to be a consequence of the correlation of O+ (S-4) and NO((2)Pi) with the excited states (3)A(1), B-3(1) of NO2+, which lie slightly above the reactants in energy. At the very high energy range, a third mechanism becomes important, probably the endothermic production of NO+((3)Sigma(+)).