<p>Electrolyte velocity distribution calculation and measurements in electrochemical reactors under two-phase flow conditions play a critical role in their design to study the scalability process of interest in the sustainability field. This work aimed to perform a coupled analysis between computational fluid dynamics, considering the Euler-Euler weakly coupled approach, experimental techniques for the characterization of the fluid regime under gas-evolved conditions (RTD curves) and direct velocity measurements employing optical techniques (PIV measurements). The analysis showed, in general, a diminishing of the average velocity magnitude in the channel as the current densities increase, fixing the flow rate and the velocity at the reactor inlet. All available theoretical and experimental evidence elucidated that a change of multiphase flow regime (maybe bubbly to slug) during electrolysis could provoke the velocity variations in our experiments, generating bubble-fluid interactions that are not taken into account in the proposed two-fluid Euler-Euler model. Results obtained with theoretical and experimental tools used here should improve the understanding of the phenomenology involved in the complicated behavior of fluid velocity distribution of a two-phase gas-evolved electrode system, and it could be useful to validate simulations performed on more sophisticated CFD models than the Euler-Euler approach used.</p> Graphical abstract <p></p>