Some early studies of the rate of solid-state reactions are briefly reviewed in connection with the later development of techniques for determining kinetic parameters under non-isothermal conditions. The fundamental kinetic equations for the non-isothermal reactions are reexamined in an attempt to increase the reliability of the kinetic parameters obtained for solid state reactions. It is suggested that reliable kinetic parameters are obtained in terms of kinetic equations with nonintegral kinetic exponents. The significance of such a kinetic approach as well as the usefulness of the reduced time are discussed and illustrated by the kinetic analysis of several decompositions of solids. It is stressed that the isoconversion methods, isothermal or non-isothermal, are quite appropriate for obtaining reliable kinetic parameters and in turn for understanding the kinetics of solid state reactions in a comprehensive and sophisticated way.