During the electrochemical analysis or disposal of most of phenolic compounds, insulated polymeric substrates are created and cover the electrode surface. This can cause the signal current to decay over time, which is called electrode fouling or electrode passivation. This paper describes a model based on the potential drop across the fouling layer that is helpful for deeper understanding of the mechanism of electrode fouling/passivation. Copper deposition and a controlled fouling process were used to verify this model and quantitatively determine the potential drop. This model successfully fitted the experimental data and describes how fouling can occur. (C) 2013 Elsevier Ltd. All rights reserved,