This study represents an effort to fit a Langmuir-Hinshelwood-type mechanism which involves a proposed hydrogen transfer step from a carbonaceous deposit with observed rate data, spectroscopic data, and reported literature results on a supported Pd/gamma -Al2O3 catalyst prepared by the sol-gel method. Our data was taken in a differential reactor as the temperature was varied from 100 to 225 degreesC in six increments. A change in the apparent reactant orders and activation energies support a multiple mechanism rate expression. Our data correlates best with an expression composed of two mechanisms: a competitive, low-temperature mechanism (mechanism I) with an activation energy of 29 kJ/mol, and a non-competitive, high-temperature mechanism (mechanism II) with an activation energy of 168 kJ/mol. Both mechanisms were fit using an enthalpy of adsorption of -124 kJ/mol for acetylene. The enthalpy of the hydrogen transfer was found to be 133 kJ/mol, indicating an endothermic process. Mechanism II is predicted to emerge and dominate at high temperatures.