The problem of nonlinear frequency response of adsorption systems is treated using the concept of higher-order frequency response functions (FRFs). The FRFs on the adsorber and on the particle scale are considered. Based on nonlinear mathematical models, expressions that correlate the higher-order FRFs of isothermal batch and flow adsorbers and the FRFs on the particle scale are derived. In the batch adsorber, there are two sources of nonlinearity : one associated with the reservoir, and the other with the adsorption process, while in the flow adsorber the nonlinearity is due to nonlinear adsorption process only. Application of the method is illustrated on the example of adsorption governed by Langmuir kinetics. The higher order FRFs on a particle and on an adsorber scale are simulated, as well as the nonlinear FR of the adsorbers.