Fossil fuels consumption rate is an important issue which needs to be addressed regarding future perspectives in terms of the world overall energy requirement due to its exhausting nature and also due to environmental concern. Hence, more diversified research for alternate sources of fuel is needed, even to the extent of using only dual fuels; a mixture of high and low viscous fuel to eliminate diesel from compression ignition (CI) engines completely. In the present study, soya and soya ethanol blends are used as fuels for the CI engine. Besides the use blends in a diesel engine, the response surface methodology technique is also implemented for getting better responses. RSM results confirm that the use of dual fuel results in satisfactory engine performance and emission in a standard diesel engine without any modification in the engine. Blends, engine speed, air flow rate, and engine load are the input variables considered for attaining better BTE, VE, CO, HC, and NOx as the responses. From all the tested fuel blends considered in the study, the result shows that a blend of soya biodiesel with 8% blending with dual fuel mode at 1486 RPM, 49.5 mm manometer air flow, 6.27 kg engine load show an overall good engine performance. The performance and emission characteristics (BTE, VE, CO, HC, and NOx emission) are found to be 24.29%, 68.53%, 0.0715% volume, 51.6 ppmv and 1080.2 ppmv respectively. (C) 2019 Elsevier Ltd. All rights reserved.