A three-parameter microcanonical theory of gas-surface reactivity is used to model the dissociative sticking of vibrationally excited methane with two quanta of energy in the nu(3) antisymmetric C-H stretch. An apparent threshold energy for C-H bond cleavage of CH4 incident on Ni(100) of 65 kJ/mol is found, in quantitative agreement with ab initio quantum chemistry calculations but 38 kJ/mol less than GGA-DFT calculations. Successful microcanonical analysis and prediction of recent thermal equilibrium and various nonequilibrium dissociative chemisorption experiments for methane on Ni(100) provide no evidence for mode-specific reactivity. (C) 2003 American Institute of Physics.