One of the fossil fuels is petroleum fuel. Petroleum is a non-renewable natural resource. Various aspects of life have felt its effects, where fuel oil has begun to experience scarcity. The higher price of fuel oil should make us realize that the amount of oil reserves has begun to run low. The purpose of this study was to determine the effect of electrodes, current strength, and concentration of NaHCO3 on the HHO gas generator output. HHO electrode generator material made of aluminum and brass. The electrode's shape is rectangular with a size of 250 mm x 400 mm, with a gasket seal. The test begins with the HHO gas pressure test. The independent variable used is aluminum and brass electrode variations. The electric current given is 20A, 30A, 40A, and the amount of 5-25% NaHCO3 catalyst. Then proceed with analyzing the pressure obtained on the HHO gas flow rate. To test the HHO gas flow rate carried out with a duration of 1 to 3 minutes in each treatment, the measurement of the discharge using a gas regulator to determine the flow rate of H2 and O2 produced. The results showed that the lowest gas discharge value was on aluminum electrodes with a current of 20A, i.e., 0,00033554 m3/s, while the highest discharge value on brass electrodes with a current of 50A was 0,001657 m3/s. It shows that the better the metal element contained in the electrodes and the higher the current applied, the greater the flow of H2 and O2 gas flow.