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The authors have recently advanced a hypothesis for the phenomenon of oscillatory adsorption suggesting that it is caused by a number of factors such as the competitive filling of the surface by A and B components, the ‘spotty’ nature of component adsorption, the dramatic change in the configuration of such ‘spots' at a certain step during surface filling with one of the components resulting in a transition of the adsorption layer from an ‘ A in B’ state to a ‘B in A’ state and vice versa, and the dependence of the values of the chemical potential of A and B on the configuration of the adsorption ‘spot’ causing a change in the direction of the sorption process. In the present communication, an attempt is made to examine the phenomenon from the viewpoint of non-equilibrium thermodynamics. By relying on the Gibbs equation, particularly with respect to the flux and affinity equations, and taking account of the equality of the reciprocal influence coefficients, it is possible to conclude that the chemical potentials of the competitive components are either equal or approximately equal at the periphery of the sorption ‘spots’. This indicates that the entropy of the system remains constant (i.e. dS = 0) leading to the possibility of sustained oscillations occurring in the adsorption process.