AbstractPerturbation chromatography previously has been used experimentally as an efficient method for obtaining sorption equilibria for systems with up to two vapor phase components at finite concentration. The objective of this work was to obtain a theoretical result that could be used for experimental determinations of sorption of multiple interfering species at finite concentration. Results obtained are applicable for both non‐stoichiometric and stoichiometric situations for systems that may have flowing phase velocity and volume changes associated with interphase transport and also may have interactions among the sorbed components. The dependence of each effluent peak characteristic velocity upon all of the component equilibrium isotherms requires that the equilibria be considered as a whole by simultaneously fitting a set of composition grid perturbation response data to appropriate isotherm surface equation