Abstract: The electrocatalytic CO2 reduction reaction (eCO2RR) technology is a promising area of research due to its mild and controllable reaction conditions and its ability to be combined with clean and renewable energy sources. In particular, membrane electrode assembly (MEA) electrolyzer have the potential for industrial application due to their compact structure, high energy efficiency and low ohmic losses. Nevertheless, existing numerical modelling studies of eCO2RR frequently fail to adequately consider the impact of acid-base equilibrium reactions in solution on the electrochemical processes. Furthermore, there is a paucity of in-depth analysis of the role of gas diffusion layer (GDL) thickness and porosity on the system performance. This paper presents a geometrical modelling of the MEA electrolyzer, which is then coupled with a dynamic and comprehensive model of