A new method has been outlined that improves the discrimination of the kinetic model fitted by a solid state reaction from a single CRTA experiment, by means of a series of master plots that represent the values of (T-0.5/T)(2)[d alpha/dT)(0.5)/(d alpha/dT)] as a function of alpha. The suffix 0.5 refers to the values of the temperature T and d alpha/dT when the fraction reacted alpha is 0.5. Kinetic analyses of the thermal decompositions of calcium carbonate and anhydrous nickel nitrate have been used to check this method.