Numerical models coupling transient radiative, convective, and conductive heat transfer and mass transfer to chemical kinetics of heterogeneous solid–gas reactions are developed and applied to selected model reactions such as the decomposition of calcium carbonate into calcium oxide and carbon dioxide (Fig. 1). This particular model reaction is one of two reactions involved in calcium oxide looping, a proposed thermochemical process suitable for use with concentrated solar radiation for the capture of carbon dioxide. The analyzed system is a porous particle in a reactor–like environment that is subjected to concentrated solar irradiation. The models predict the time-dependent temperature distributions as well as local solid and fluid phase composition. They are used to investigate operating conditions under which actual solar-driven processes can attain high reaction extents and efficiency.