Numerous studies have demonstrated the diesel fuel characteristics vary by adding the biodiesel. Furthermore, the nanoparticles or catalysts can mix with these fuels to improve their performance and exhaust emission characteristics. In this study, the Carbon Nanotubes (CNTs) as an additive were mixed with the B5 and B10 fuel blends to evaluate the performance and emission of a CI single-cylinder engine. The CNTs with the concentrations of 30, 60, and 90 ppm were used for each fuel blend. Tested characteristics were power, brake thermal efficiency (BTE), specific fuel consumption (SFC), exhaust gas temperature (EGT), and emissions of CO, CO2, unburned hydrocarbons (UHC), NOx, and soot for full load engine at speeds of 1800, 2300, and 2800 rpm. It was observed the CNTs added to fuel blends exhibit considerable enhancement in power (3.67%), BTE (8.12%), and EGT (5.57%) at all engine speed. The results also showed a significant reduction in SFC due to influence of added CNTs in diesel-biodiesel blend. The results of emissions characteristics showed the CO, UHC, and soot exhaust emissions decreased, and NOx emissions increased. There was a negative statistical correlation between the CO and CO2 emissions. Moreover, enhancing the EGT had an important role in NO. emission. (C) 2017 Elsevier Ltd. All rights reserved.