The decomposition of methyl iodide on Ni(111) surface alone or in presence of hydrogen gives rise to the desorption of methane which appears as two peaks at two distinctly different temperatures (150 and 250 K) in the course of a temperature programmed desorption study (TPD). The method of bond order conservation-Morse potential (BOC-MP) analysis has been employed to rationalize the experimental findings by calculating the energies associated with the envisaged routes of the reactions. It is concluded that methyl groups adsorbed on 3-fold sites react with adsorbed hydrogen atoms with an activation energy of 14 kcal/mol to form gaseous methane desorbing at 250 K. The methyl group made mobile upon the crowdedness of the surface and traversing over on-top sites and having higher energy than the methyl groups adsorbed on 3-fold sites react with hydrogen with zero activation energy and forms the methane peak at 150 K in the TPD regime. The cleavage of C-I bond with an activation energy of 3 kcal/mol constitutes the rate determining step. The prediction capabilities of the method are further proven by briefly considering the process on Ni(100) and Ni(110) surfaces where in the former excellent agreement with the experimental findings is met and in the latter the theoretical findings are brought, to the attention of the experimentalist.