In this study, an experimental work was conducted in a naturally aspirated, 4-stroke, 4 cylinder direct injection compression ignition engine operated with diesel-soybean biodiesel-hydrogen combinations as fuels and aluminum oxide (Al2O3) as nanoparticle additive. Engine tests were carried out between 1200 rpm and 2800 rpm engine speeds by 400 rpm intervals at full load condition. Each tests were repeated three times and results were averaged in order to ensure to gather more accurate results. Power and brake specific fuel consumption (BSFC) as performance and carbon monoxide (CO), carbon dioxide (CO2) and oxides of nitrogen (NOx) as emission characteristics of the engine were determined. Nanoparticle additive was mixed with fuels with the help of an ultrasonic processor. Hydrogen enrichment was achieved through intake manifold. Experiments have exhibited that deteriorations on engine performance with biodiesel utilization can partially or fully be compensated with nanoparticle addition and hydrogen supplementation. CO emission was reduced in all fuels in comparison to diesel fuel. Adverse effects on CO2 emission as a result of biodiesel and nanoparticle additive usage can be eliminated a bit by hydrogen since it has superior combustion characteristics. Unfortunately, all test fuels trigger more NO x release compared with diesel fuel. H-B20-A demonstrated best performance characteristics with 6.64% rise in power and 2.72% reduction in BSFC compared to diesel fuel. Most reduction in CO (15.91%) was achieved with H-B100-A. Least increase in CO2 compared to diesel fuel (6.1%) was realized with H-B20-A while the least CO2 was observed with diesel fuel. In NOx emission, all fuels exhibited more release than diesel fuel. But least rise was observed with B20 as 6.73% in comparison with diesel fuel. (C) 2021 Karabuk University. Publishing services by Elsevier B.V.