The mechanism for the C 2 H 3 + CH 3 OH reaction has been investigated by the Gaussian-4 (G4) method based on the geometric parameters of the stationary points optimized at the B3LYP/6-31G(2df, p) level of theory. Four transition states have been identified for the production of C 2 H 4 + CH 3 O (TSR/P1), C 2 H 4 + CH 2 OH (TSR/P2), C 2 H 3 OH + CH 3 (TSR/P3), and C 2 H 3 OCH 3 + H (TSR/P4) with the corresponding barriers 8.48, 9.25, 37.62, and 34.95 kcal/mol at the G4 level of theory, respectively. The rate constants and branching ratios for the two lower energy H-abstraction reactions were calculated using canonical variational transition state theory with the Eckart tunneling correction at the temperature range 300-2500 K. The predicted rate constants have been compared with existing literature data, and the uncertainty has been discussed. The branching ratio calculation suggests that the channel producing CH 3 O is dominant up to about 1070 K, above which the channel producing CH 2 OH becomes very competitive. C 2015 Wiley Periodicals, Inc. Int J Chem Kinet 47: [764][765][766][767][768][769][770][771][772] 2015