In this work, we develop non-equilibrium information theory formalism for the investigation of the steady-state heterogeneous electron transfer. In order to analyze the information transfer, we introduce the concept of information potential and information affinity. These new functions allow us to describe the transformation from the initial to final state by means of Fokker-Planck type equation. Accordingly, the transformation can be viewed as a diffusion process within the phase space. Also, we are able to determine the information entropy production. We show that the Shannon information entropy production is equal to zero for a reversible system. However, the change in the relative entropy or Kullback-Leibler measure of information distance is positive for an irreversible system. In all cases, we find that a non-negative information entropy production is always observed during the experiments. Here, we demonstrate the self-consistency of the non-equilibrium formalism in the information theory for studying steady-state electrochemical systems. (C) 2010 Elsevier B.V. All rights reserved.