This work is devoted to the study of hydrodynamics behavior and mass transfer performance in water electrolysis processes, two configurations of containers and electrodes are studied in laboratory experiments under different current densities, the platinum (0.2 mm in diameter) in an acidic environment (36% CH3COOH) as electrode material, surrounds the sides of the container in horizontal mode. The system is studied using particle image velocimetry (PIV), microscope enhanced visualization. The experimental results show that the velocity distribution in most regions of electrolyser is dominated by two asymmetry bubble buoyancy induced flow patterns. The greater reaction rate of water electrolysis and better mass transfer arise in the smaller space of electrodes. By comparing hydrodynamic behavior in two containers with different current densities, hydrogen production, bubble-driven convection and convective mass transfer increase at higher current densities, however, this increase is not linear, the interaction mechanisms are analyzed on mass transfer, electrochemical reaction and bubble effect. Results facilitate the understanding and the design of the transport phenomena in electrolyser.