The effect of using dual alcohols (n-butanol and iso-butanol) blended into gasoline fuel on spark-ignition (SI) engine performance and pollutant emissions is experimentally investigated. Three blend rates are applied (3, 7 and 10 vol.% iso-butanol and n-butanol) as well as the neat gasoline as a base fuel; such dual blends are thought the first of their kind in internal combustion engines. The engine performance (brake power, BP, torque, Tq, volumetric efficiency, VE, pressure inside cylinder, P, and exhaust gas temperature, EGT) and pollutant emissions of CO, UHC (unburned hydrocarbons) and CO2 were examined at engine speeds of 2600-3400 r/min for each blend rate and base fuel. In addition, engine performance and pollutant emissions of dual alcohols/gasoline blends were compared with those of single alcohol/gasoline blends, e.g., iso-butanol-gasoline and n-butanol-gasoline blends. Results demonstrate a higher performance and lower emissions when engine operated with dual alcohols/gasoline blends, compared to single ones. Dual alcohols with 10 vol.% of n-butanol/iso-butanol blended in gasoline monitored the best performance and emissions among all the fuel blends (single or dual alcohols). However, results showed also a decrease in VE, BP, Tq, P and EGT when engine operated with the dual alcohols compared to base fuel. Nevertheless, performance of the dual alcohols can exceed those of the base fuel by increasing the blend rate value. Besides, dual alcohols burn cleaner than regular gasoline and produce slighter CO, CO2 and UHC pollutants by about 4.3%, 40% and 11%, respectively, compared to base fuel. (C) 2015 Elsevier Ltd. All rights reserved.