In this present work, investigations are carried out to study the performance and emission characteristics of adding hydrogen peroxide (H2O2) as an additive with the selected ratio of the emulsified fuel. The results are compared to diesel number 2 and the selected emulsified fuel ratio of 50D/50E. For this experiment, a single-cylinder, four-stroke, water-cooled diesel engine is used. Initially, the engine is run with diesel number 2 fuel, and the readings are recorded. Then, the engine is run with the emulsified fuel ratio of 50D/50E on a volume basis, and the readings are taken into account. Finally, along with the emulsified fuel ratio 50D/50E, the additive hydrogen peroxide is added at 12% by volume basis, and the readings are also being observed. On the basis of the test results, the hydrogen-peroxide-added emulsified fuel shows an increase in brake thermal efficiency and a decrease in specific fuel consumption, smoke density, particulate matter, oxides of nitrogen, hydrocarbon, and carbon monoxide than the diesel fuel number 2 and the emulsified fuel.