In the present study, the electrochemical model for a newly designed photo electrochemical hydrogen production reactor is discussed. The reactor integrates the photochemical hydrogen production with an electrochemical chloralkali process. To neutralize the hydroxyl ions into the chloralkali process, the ideal minimum required potential is 2.18 V. However, there are losses in the solution, membranes and electrodes. These losses should be calculated to find the exact voltage requirement of the photoelectrochemical hydrogen production reactor. An electrochemical model is developed to calculate these losses in the reactor. Effect of brine concentration, electrolyte concentration, distance between the electrodes, current density and temperature are evaluated. The results show that a minimum voltage is required when the distance between the electrodes becomes a minimum at the highest possible temperature, lowest current density and at highest concentrations of brine and electrolyte. Furthermore, they indicate that brine and electrolyte concentrations do not have significant effect on required voltage. (C) 2014 Elsevier B.V. All rights reserved.