By reviewing various microscopic studies on the mechanisms of the thermal dehydration and/or decomposition reactions of inorganic solids, the physico-geometric and chemical features of the solid-state reactions were investigated. A model of reaction interface and a classification of interfacial chemical behavior for the thermal dehydration of solids, which have extensively been studied by professors Galwey and Brown, were introduced in order to evaluate the significance of such mechanistic understandings on the solid-state reactions. The meanings of the kinetic models and kinetic equations, which have been employed conventionally for analyzing the overall kinetics of solid-state reactions, were discussed in relation to the complicated physico-geometric and chemical behaviors of the solid-state reactions revealed by the mechanistic investigations. Possible extensions of the conventional kinetic theory by incorporating various physico-geometric and chemical features were examined for an advanced kinetic understanding of the solid-state reactions. The kinetic data required for the advanced kinetic analysis of the solid-state reactions were discussed by emphasizing the usefulness of the controlled rate thermal analysis (CRTA). The present status and future subjects of the kinetic and mechanistic studies on the solid-state reactions were summarized briefly through the present review.