The influence of dissolved several inorganic contaminants into water was examined on the decomposition of aqueous organic compounds by direct contact of gas corona discharge. It was found that addition of 0.01 mol 1(-1) NaOH into water significantly improves the decomposition of aqueous phenol while the addition of HCl of the same concentration inhibits the decomposition rate. As it is known that phenol is converted to stable acetic acid during the decomposition process in the reactor, the influence of NaOH, HCl, H3PO4 and NaCl was examined on the degradation of acetic acid. As a result, dissolved Cl- inhibits its decomposition efficiency. It is also found that this decomposition rate is significantly improved by raised pH which is higher than 11. (C) 2003 Elsevier B.V. All rights reserved.