Measurements have been made over a wide range of mixture composition of the yields of cis- and trans-but-2-ene, but-1-ene, isobutene and methane, when propene is added to slowly reacting mixtures of H₂ and O₂ at 480 °C. From the initial yields of the butenes relative to that of methane, rate constants have been determined for the overall addition of CH₃ radicals to propene and for specific terminal and non-terminal addition. Values of k_int= 2.18 × 10⁶, k_lt= 1.60 × 10⁶ and k_ln= 5.8 × 10⁵ dm³ mol^–1 s^–1 at 480 °C are obtained. [graphic omitted] Combination with low-temperature data for the overall addition gives A_1nt=(2.57 ± 0.83)× 10⁸ dm³ mol^–1 s^–1 and E_1nt= 30.3 ± 3.2 kJ mol^–1 over the range 80–480 °C. Combination of the present results with the very limited low-temperature data for specific addition gives A_1t= 10^{8.25 ± 0.25} dm³ mol^–1 s^–1 and E_1t= 29.5 ± 3 kJ mol^–1, and A_1n= 10^{8.30 ± 0.30} dm³ mol^–1 s^–1 and E_1n= 36.5 ± 5 kJ mol^–1. The main cause of the selectivity thus appears to arise from activation-energy differences as suggested for H-atom addition to propene. A maximum value of the rate constant for abstraction at the allyl position in propene by CH₃ radicals has been determined at 480 °C and combined with low-temperature data to give maximum values of A= 4.4 × 10⁷ dm³ mol^–1 s^–1 and E= 31.5 kJ mol^–1. Arising from the difference in the A factors and the almost identical activation energies for addition and abstraction, then addition will always be the more important primary process, but at combustion temperatures reverse decomposition of the methyl adducts will reduce the importance of addition and abstraction will predominate.