Flow hydrodynamics and mass transfer have been investigated using numerical simulation and validated using experimental measurements. UV-vis measurements have been obtained to determine the apparent heterogeneous rate constant, k(app), and adsorption-desorption equilibrium constant, K, of the electrochemical oxidation of p-methoxyphenol (PMP). Generation of gas bubbles was visualized using a high-speed camera, and MATLAB was used to obtain the average void fraction. The experimental results show good agreement with simulation results. Two-phase bubbly flow has been described by a mathematical model based on the Euler-Euler approach. To accurately predict the two-phase bubbly flow in an electrolyzer, a developed model of interfacial area concentration has been adopted for bubble size effects. This study shows that different operating conditions affect the void fraction and gas bubble layer. Additionally, the mass transfer efficiency and mass transfer correlations have been investigated in order to design the optimal experiments for electrochemical oxidation.