This work presents a study of discharge characteristics and generation of reactive species such as OH center dot radical, hydrogen peroxide, and ozone by a gas-phase dielectric barrier discharge (DBD) process. A series of experiments were performed to investigate the effects of various parameters such as input energy density, feeding gas, gas flow rate, and electrode gap on the formation of OH center dot radical, hydrogen peroxide, and ozone in solution. The pH and N-containing products (NO2- and NO3-) in solution were also determined. The experimental data show that formation rates of OH center dot radical, hydrogen peroxide, and ozone in solution were found to depend on the input energy density, feeding gas, gas flow rate, and electrode gap. When pure oxygen was used as the feeding gas, O-3 was the major reactive species. The OH center dot radical was observed to be the major reactive species generated and its concentration was approximately 12 times higher than that of O-3 when air with 100% relative humidity (RH) was used as the feeding gas. NO3- byproducts fornied in the solution were partly responsible for the pH decrease.