A device that uses electrical discharges/nonthermal plasmas in a gaseous medium to activate a fuel or fuel-oxidizer mixture to promote more effective and efficient combustion, in which a dielectric barrier discharge or silent discharge plasma is used to break up larger organic molecules (the fuel) into smaller ones that are more easily and completely combusted. The discharge also creates free radicals that promote more efficient combustion. The device is a cylindrical, coaxial (cylinder in a cylinder) dielectric barrier discharge/silent discharge plasma reactor. It includes two conducting electrodes, one or both of which are covered by a dielectric material. The electrodes are separated by a thin, gas-containing space. A high voltage is applied to the electrodes to create electric discharge streamers in the gas. The discharges are the source of the nonthermal plasma.