AbstractDue to limited stock of levels of fossil fuel resources and ecological issues, biodiesel is becoming an attractive alternative choice for replacing conventional fuels. Biodiesel can be used by mixing with different fuels like citrullus lanatus seeds, camphor, cleaner fuel injector, sunflower, safflower, soybean, cottonseed, rapeseed, palm, Jatropha, and Moringa oil seeds.This paper reviews use of biofuels blended with citrullus lanatus seeds. The citrullus lanatus biodiesel was mixed with diesel in different percentages by volume. Some physico‐chemical characteristics of blends and pure diesel were investigated and it was established that it conforms to the American Society of Testing Materials (ASTM) standards. The exceptions were the viscosity and specific gravity of the pure biodiesel B100 which were 0.09 and 0.018 mm2/s above the ASTM standard, respectively. All blends were run on a stationary 4‐cylinder diesel engine at 70% loading and speeds of 1500, 2000, and 2500 rpm. It was deduced that B10 gave the best brake power, thermal efficiency, and optimum specific fuel consumption at a speed of 2500 rpm. B15 gave the highest brake mean effective pressure. B25 and B100 gave the least values of brake power and brake thermal efficiency across the speeds. B100 gave the highest brake specific fuel consumption. Furthermore, the exhaust emission gases such as CO2, CO, NOx, and HC in different engine conditions stated above were recorded and analyzed. It was found that B25 emitted about 53% lesser CO2 and 37% lesser CO as compared to pure diesel with zero HC at 2500 rpm. The blends were better in terms of engine performance and also in reduction of emissions in most cases, than pure diesel fuel.Problem statement: Various emissions from engines like unburnt hydro carbons, particulate emissions, NOx, and CO have bad effects on ecology. This work presents an overview on use of novel hybrid fuels in compression ignition engines with an aim of mitigating effects of emissions on environment. Biodiesel was blended with Citrullus lanatus oil and pure diesel in different proportions to see effects on performance of diesel engines. The presented work may pave the way for use of alternative cheap and environmentally friendly fuels in automotive systems.