© 2020 Elsevier LtdAggregating pollution along with exhausting fossil fuels throughout the world has enforced the inventors to explore for an alternative fuel that can be utilized in diesel engines. Presently, investigators and professionals have originated that biodiesel in association with higher alcohols and gaseous fuel can be an alternative for the current circumstances. Anterior examinations have rendered that biodiesel and higher alcohol along with gaseous fuels can support in upgrading the performance and denigrating detrimental exhaust emanations in a diesel engine. This research aimed to investigate the impacts of engine load, n-butanol concentration, and biogas quantity on emissions and performance characteristics of a small utility compression ignition engine. The different engine load (20–100% of brake power), n-butanol concentration (0–20%) and biogas flow rate (0.5–2 kg/h) were used as input variables. The multi-criteria decision analysis based on response surface method techniques was employed to find the optimal values of engine working conditions fuelled with diesel/n-butanol/biogas fuel blends. In the optimization process, five objective functions (BTE, NOX, CO, UHC, and soot) were considered to be optimized based on the defined criteria. The addition of n-butanol in diesel has shown a favourable impact on biogas operated dual-fuel engine in terms of performance and emissions characteristics. The approach of desirability was applied to obtain the best operating conditions of the engine. The optimum value of engine load, n-butanol concentration, and biogas flow rate were found as 78.89%, 20%, and 1.37 kg/h, respectively. At this condition, the optimal value of BTE, UHC, CO, NOX, and smoke emissions were found to be 19.19%, 0.36g/kWh, 0.04%, 14.51g/kWh, and 22.32%, respectively. A high desirability value of 0.77 was obtained for the suggested condition, showing the efficiency of the derived models for response parameters.