This study aims to investigate the effects of palm or coconut biodiesel blend and their combination on the performance and emissions of a single-cylinder diesel engine. A 20% v/v blend of palm biodiesel (PB20) or coconut biodiesel (CB20) and varying percentage mixtures of these two feedstocks (PB15CB5, PB10CB10, and PB5CB15) were used in the experiments. Biodiesel was produced using one-step transesterification. Physicochemical analysis showed that both palm and coconut biodiesel met the specifications of ASTM D6751. A 10 kW, horizontal, one-cylinder, four-stroke direct injection diesel engine was used to carry out tests under full load conditions at varying speeds from 1400 to 2400 rpm with an interval of 200 rpm. Burning of CB20 reduced break power by 1.72% and increased brake-specific fuel consumption (BSFC) and NOx emission by 4.07% and 4.49%, respectively. Conversely, burning of PB20 negligibly reduced brake power and increased NOx emission by only 1.79%. Meanwhile, combined palmcoconut biodiesel at a constant final blend reduced NOx emission by 0.54% to 1.85% and slightly improved brake power and BSFC. Thus, the advantages of the high cetane number of coconut and the high ignition quality of palm biodiesel were aggregated in the combined blends