Thermodynamic and kinetic parameters for the reaction HI + CH3 = I + CH4 are calculated using high-level ab initio molecular orbital methods. Activation enthalpies at 0 K for the forward (0.33 kJ mol(-1)) and reverse (137.29 kJ mol(-1)) reactions are reported for the first time. Calculated reaction enthalpy Delta H-r(0K) (-136.96 kJ mol(-1)) is in perfect agreement with its literature counterpart. Canonical transition state theory with an asymmetrical Eckart tunneling correction is used to predict the rate constants as a function of temperature (250-2500 K). (C) 2011 Elsevier B.V. All rights reserved.