A new coupled bio-diesel surrogate and primary reference fuel (PRF) oxidation skeletal mechanism has been developed. The bio-diesel surrogate sub-mechanism consists of oxidation sub-mechanisms of Methyl decanoate (MD), Methyl 9-decenoate (MD9D) and n-Heptane fuel components. The MD and MD9D are chosen to represent the saturated and unsaturated methyl esters respectively in bio-diesel fuels. Then, a reduced iso-Octane oxidation sub-mechanism is added to the bio-diesel surrogate sub-mechanism. Then, all the sub-mechanisms are integrated to a reduced C-2-C-3 mechanism, detailed H-2/CO/C-1 mechanism and reduced NOx mechanism based on decoupling methodology. The final mechanism consisted of 68 species and 183 reactions. The mechanism was well validated with shock-tube ignition delay times, laminar flame speed and 3D engine simulations. (C) 2015 Elsevier Ltd. All rights reserved.