This paper analyzes the effect of antioxidants on engine combustion performance of a multi-cylinder diesel engine fueled with rubber seed biodiesel blends. Four antioxidants, namely 2-tert-butylbenzene-1,4-diol, N,N�-diphenyl-1,4-phenylenediamine, 2(3)-tert-Butyl-4-methoxyphenol and N-phenyl-1,4-phenylenediamine, were added at concentrations of 1000 and 2000 ppm to rubber seed biodiesel blends. Antioxidants blends increased the brake power by 4.21 and decreased the brake-specific fuel consumption by 6.82 compared to base biodiesel blends. The NO emissions reduction percentage for antioxidants fuels was 9.78 compared to base line biodiesel. However, the treated biodiesel blends increased carbon monoxide, hydrocarbon and smoke opacity up to 32.20, 42.15 and 43.92, respectively, compared to non-treated blends. Compared to diesel fuel, antioxidants fuels decreased the brake power and increased the brake-specific fuel consumption, cylinder pressure and heat release rate. But compared to biodiesel blends, the cylinder pressure and heat release rate with antioxidants were reduced by 4.17 and 6.87, respectively. It can be concluded that antioxidants addition is effective in increasing the oxidation stability and controlling the NO emissions of rubber seed biodiesel fueled diesel engines. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature.