A comparative study of the reactivity between copper(I) chloride and three types of Cu3Si obtained in a molten medium (Cu3Si-Ref) and from mechanical activation following an annealing process (Cu3Si-M2AP) or a self-propagating high-temperature synthesis (Cu3Si-MASHS) was performed by thermogravimetry under vacuum using non;isothermal and isothermal methods of kinetic measurement. It was established that for the three Cu3Si/CuCl systems, the acceleration and decay stages in the temperature range 145-215 degrees C are very closely approximated by an equation of the Prout-Tompkins type where an autocatalytic process was proposed. The lower apparent activation energy obtained for the Cu3Si-MASHS/CuCl system (63 kJ mol(-1) against 68 and 78 kJ mol(-1) for Cu3Si-M2AP and Cu3Si-Ref, respectively) has been attributed to a small grain size which induces nanoscale contacts between reactants and impedes CuCl to sublime.