This present work highlights the influence of injection timing (IT), injector opening pressure (IOP) and compression ratio (CR) on the combustion characteristics of a diesel engine operated on renewable and sustainable fuels. In this research work an effort has been made to enhance the combustion of fuel combination in a diesel engine with addition of carbon free hydrogen and in the direction of lowering the exhaust emission levels. Experimental investigations have been carried out to study the combustion and exhaust characteristics of a single cylinder, four stroke, direct injection (DI) diesel engine operated on Tri-fuel mode using Honge seed oil methyl ester (HsOME) as the injected fuel and producer gas-hydrogen mixture as the inducted fuel.. To minimize the number of experiments full factorial design (FFD) has been adopted. The response surface methodology (RSM) based quadratic models obtained through FFD have been established between the parameters and proposed characteristics. With hydrogen addition, response surface analysis showed that increasing CR, IOP with advanced IT significantly improves the combustion of HsOME-producer gas fueled diesel engine in terms of the enhanced brake thermal efficiency (BTE) and reduced carbon based emission levels (Smoke opacity, Carbon monoxide, Hydrocarbon) except the nitric oxide (NOx) emissions. Further combustion parameters such as Ignition delay (ID), and combustion duration were lowered with hydrogen addition, advanced IT, increased lOP and CR. In addition peak pressure and heat release rate (HRR) were found to be higher compared to base fuel combination. (C) 2019 Elsevier Ltd. All rights reserved.