The performance and emission characteristics of conventional diesel fuel and biodiesel blends of 20, 40 and 50 from waste cooking oil (WCO) based on hydrodynamic cavitation (HC) have been compared and found to be acceptable according to the EN 14214 and ASTM D 6751 standards. The tests have been operated in an In-line vertical six cylinder diesel engine at different engine speeds ranging 1,000 to 2,000 rpm under full throttle load. The experimental results showed that biodiesel blends had higher brake specific fuel consumption (3.8-9.0 ) and exhaust gas temperature (2.3-6.8 ), while lower brake power (2.6-6.7 ), torque (1.4-5.2 ) and brake thermal efficiency (3.7-8.4 ) than diesel fuel. Engine emissions showed higher CO2 (18.8-38.5 ) and NOx (7.5-19.0 ), but remarkable decreased of CO (6.8-26.3 ) compared to diesel fuel. Higher CO2 is emitted, but it is greatly reduced from the view of the life cycle circulation of CO2 (carbon footprint). Low cost of WCO through HC is a simple scale up, energy efficient, time saving and eco-friendly make biodiesel viable for industrial production and also can be used without any engine modifications as an alternative and environmental friendly fuel. Copyright © 2016, AIDIC Servizi S.r.l.,.