A method for quantification of the gas pulse transport in the TAP (temporal analysis of products) reactor system is presented. Particular components of the TAP reactor system that are considered include the high-speed pulse valve, the packed-bed microreactor, and the high vacuum system. The model developed for the pulse valve allows an a priori evaluation of the inlet pulse intensity as a function of feed gas conditions and valve settings. Two independent models that account for simultaneous diffusion, adsorption, and desorption are developed for the packed-bed microreactor. The first model describes the transient response of the microreactor packed with nonporous particles and is primarily intended for assessment of gas pulse transport in the interparticle region and on the particle surface. The second model is similar, except that it accounts for diffusion of the gas pulse in porous particles. Molecular beam transport and an evaluation of backscattering in the vacuum system behind the microreactor are also quantified. Evaluation of model parameters by a time-domain parameter estimation technique is also described and illustrated through several applications including estimation of diffusivities and desorption parameters. The modeling approach presented here forms a basis for further quantification of TAP studies.