A new moment-based theoretical approach for the analysis of TAP (temporal analysis of products) pulse-response data is described. The distinguishing feature of this approach is that the variables of the set of ordinary differential equations that comprise the model are moments instead of concentrations. The moments are functions of the reactor axial coordinate, whereas concentrations are functions of space and time. The theoretical framework for the extraction of kinetic parameters using this approach is developed, and is used to determine kinetic parameters for CO oxidation over platinum powder. A new phenomenon, called "TAP equilibrium" is described. This phenomenon is governed by the interplay between reaction and Knudsen diffusion.