The calculation results of the parameters of an electrolysis cell are presented. It is revealed that the current density is a parameter that needs optimal selection in the course of design of electrolysis batteries. In addition, it is found that, with a decrease in the angle of inclination of the voltage—current characteristic of an electrolyzer, its dimensional specifications improve. As a result of theoretical analysis, the dependence was found to calculate the optimal current density, which made it possible to find methods to improve the mass—dimensional and energy characteristics of electrolyzers.