The method of wastewater treatment by electroflotation is based on the electrochemical process of obtaining a gas dispersion. Features of the chemical composition of wastewater affect the electrochemical processes of water decomposition and the excretion of electrolysis gases. The aim of the research was to study the regularities of the separation of electrolysis gases from the ratio of the areas of polar electrodes and the value of the active reaction of the treated water (pH). It is established that the optimum value of the ratio of the electrode areas (fa: fc) close to 1. The value of the current density at the electrodes is recommended to take in 150 - 200 A/m2. An increase in the current density leads to heating of the liquid and an over-expenditure of electricity. The greatest influence of the pH of wastewater on the process of gas excretion is noted in the acidic medium. The gas yield is independent of the pH value in neutral and alkaline media. The gas yield remains practically unchanged with a current density of more than 150 A/m2 over the entire range of pH changes from 2 to 12. © The Authors, published by EDP Sciences, 2018.