Now a day’s pollution increasing by petroleum fuels day by day in India as well as in the whole world and as we know petroleum fuels are non-renewable so a shift in scientist’s interests, recently observed, toward lower Fuel consumption and emission engines take place. This encourages researchers to seek alternative solutions to be used in engines without the need for a dramatic change in the vehicle design so the scientific society works as an alternative fuel. In many alternatives oxyhydrogen (HHO) gas is one of the best options. HHO gas can be reduced the percentage of HC and CO. This review study deals with the use of oxyhydrogen gas four stroke petrol engines for stationary devices like electricity generator.