One of Global issue is reducting fuel fossil consumption and less emissions in internal combustion engines. HHO gas is a stable cluster of oxygen and hydrogen atoms, their dimers H–O, oxygen (O2) and hydrogen (H2) molecules and unreacted H2O. The blend of this composition makes for shorter flame development and propagation periods that improve efficiency and lower emission level in the combustion chamber. This experimental research aims to determine the effect of HHO gas in gasoline generator engines with load variations. The amount of CO gas and fuel consumption measured when the engine is operating. This research uses an electrolyte liquid with a mixture of 7 g of NaOH and 1000 ml of water which is stirred until it dissolves homogeneously. The electric current passes 6 through stainless steel plate that has been arranged in an electrolyte solution, so that the flowing electric current will cause the formation of HHO gas in the outlet connected to the manifold. Adding HHO increased the engine’s starting capacity from 353 to 552 s at a load of 100 watts. Furthermore, the use of HHO generators in petrol engines has a beneficial effect on exhaust emissions, demonstrated by the decrease in CO levels when compared to running the engine without a hydrogen generator.