This study investigates the effects of adding diethyl ether (DEE) and moringa oleifera antioxidant (MA) to jatropha biodiesel-diesel blended fuel on the performance and emission characteristics of a compression ignition (CI) engine. The research aims to enhance the oxidative stability and other physicochemical properties of jatropha biodiesel, which is known for its poor oxidative stability. Jatropha and moringa seeds were mechanically extracted, and the oils were processed through transesterification using methanol and potassium hydroxide (KOH) as catalysts. The resulting biodiesels were characterized for density, kinematic viscosity, calorific value, and oxidative stability. Blends of jatropha biodiesel with and without DEE and MA additives were then tested in a single-cylinder, four-stroke engine. The results showed that the addition of 5% DEE and 10% MA improved the oxidative stability of jatropha biodiesel from 2.82 hours to 15 hours. The blends also exhibited improved density, kinematic viscosity, and calorific value. Engine performance tests revealed that the brake power, brake torque, and brake thermal efficiency increased, while brake specific fuel consumption decreased. Additionally, the exhaust emissions of carbon monoxide, unburned hydrocarbons, and nitrogen oxides were significantly reduced. The study concludes that a 20% blend of jatropha biodiesel and diesel containing 10% MA and 5% DEE can be used in CI engines without modifications and with high oxidation stability.This study investigates the effects of adding diethyl ether (DEE) and moringa oleifera antioxidant (MA) to jatropha biodiesel-diesel blended fuel on the performance and emission characteristics of a compression ignition (CI) engine. The research aims to enhance the oxidative stability and other physicochemical properties of jatropha biodiesel, which is known for its poor oxidative stability. Jatropha and moringa seeds were mechanically extracted, and the oils were processed through transesterification using methanol and potassium hydroxide (KOH) as catalysts. The resulting biodiesels were characterized for density, kinematic viscosity, calorific value, and oxidative stability. Blends of jatropha biodiesel with and without DEE and MA additives were then tested in a single-cylinder, four-stroke engine. The results showed that the addition of 5% DEE and 10% MA improved the oxidative stability of jatropha biodiesel from 2.82 hours to 15 hours. The blends also exhibited improved density, kinematic viscosity, and calorific value. Engine performance tests revealed that the brake power, brake torque, and brake thermal efficiency increased, while brake specific fuel consumption decreased. Additionally, the exhaust emissions of carbon monoxide, unburned hydrocarbons, and nitrogen oxides were significantly reduced. The study concludes that a 20% blend of jatropha biodiesel and diesel containing 10% MA and 5% DEE can be used in CI engines without modifications and with high oxidation stability.