With the burning of 1 L of diesel fuel, approximately 3 kg of greenhouse gas is released into the atmosphere. Therefore, it is of great importance to reduce emissions with some additives in diesel engines. This study deals with the impacts of blends of waste cooking oil methyl ester and various metal-oxide based nanoparticles on the emission, combustion, performance, vibration and noise characteristics of a single-cylinder diesel engine. The test engine was loaded at different engine loads of 2.5, 5, 7.5 and 10 Nm and a constant engine speed of 2000 rpm. In this investigation, various fuels [called as reference diesel (D100), 10 vol% of waste cooking oil methyl ester (B10), and finally the mass fractions of 100 ppm aluminium oxide (B10Al(2)O(3)), titanium oxide (B10TiO(2)) and silicon oxide (B10SiO(2)) into the B10, separately] were tested. The addition of metal-oxide based nanoparticles has firstly increased the viscosity, cetane number, and heating value of biodiesel. Higher oxygen atoms in biodiesel-nanoparticles blends have improved the quality of the combustion process. Higher peak point in CPmax and HRRmax could be reached in these nano fuels due to their lower cetane numbers than that of D100. CO, HC and NOx emissions were significantly reduced with the blending of nanoparticles and biodiesel in comparison with those of D100. The addition of nanoparticles highly improved engine performance. B10 had the lowest thermal efficiency due to its heating value, but its efficiency was converted to the highest one with the addition of nanoparticle. In conclusion, this study is suggesting that the addition of metal-oxide based nanoparticles into biodiesel blends can give better results than using biodiesel alone for diesel engines.