Fuel additives have been used to improve engine performance and also to reduce the pollutant emissions that occur after the combustion in engine. The effect of additions of bis-(N,N-dimethyl-N'-2-chloroben zoylthioureato) palladium (II), PdL2 and bis-(N, N-dimethyl-N'-2-chlorobenzoylthioureato) nickel (II), NiL2 complexes into diesel as metal additives was investigated experimentally. PdL2 and NiL2 complexes were added as 50 and 100 ppm to diesel and the properties (density, viscosity, calorific value, Cetane number, sulphur content, flash point, pour point and copper strip corrosion) of each test fuel were investigated. In general, the metal additives haven't led to major changes on fuel properties of diesel. However pour point values of additive blends reduced while flash point increased compared to diesel. All blends were tested in a four stroke single cylinder diesel engine to find out the performance and emission characteristic. The results revealed that the use of PdL2 and NiL2 complexes nickel has no significant effect on engine torque and brake power while considerable decrease was obtained for engine pollutant emissions (CO, NOx and smoke). Also the brake specific fuel consumption (BSFC) showed overall declining trend. (C) 2015 Elsevier Ltd. All rights reserved.