The difficulty to realise a direct electronic transfer between a molecule and an electrode often necessitates the addition of an electronic mediator in organic or biochemical ekctrosynthesis processes. Modelling these processes is generally possible by using the analogy between electrode-solution systems and gas-liquid interfaces. Nevertheless, the occurrence of dismutation of the electrochemical mediator does not have a direct correspondence in studies concerning gas-liquid systems. The gas-liquid methodology and particularly the Van Krcvelen type of approach was used here to study the influence of the mediator dismutation on two basic instances. The difficulty in modelling, due to the rate of the dismutation reaction compared with the other physicochemical phenomena, was dealt with by introducing the dismutation equilibriwn into a suitable linear combination of differential mass balance equations. They were solved with an explicit finite-difference scheme. The effect of dismutation is only felt in a range of intermediate values of the Hatta number. It is quantified in the case of a pseudo-first-order homogeneous reaction. The aim to obtain a numerical tool capable of modelliig bioelectrochemical synthesis processes involving a flavinic mediator underlies the study as a whole.