Method of decomposing organic compounds

A method of decomposing an organic chemical, comprising the steps of:

• supplying a first electrolytic chamber which houses an anode plate and a cathode plate with an ion-permeable membrane interposed therebetween, with raw water containing an electrolyte as chloride ions;
• electrolyzing the raw water;
• electrolyzing only electrolyzed water obtained at a cathode side in said first electrolytic chamber, at an anode side in a second electrolytic chamber which houses an anode plate and a cathode plate with an ion-permeable membrane interposed therebetween for thereby generating hydroxyl radicals in the electrolyzed water, wherein hydroxyl radicals exist in the electrolyzed water at least three hours after the electrolysis;
• adding the electrolyzed water containing the hydroxyl radicals to water containing an organic chemical to cause the hydroxyl radicals to attack to the organic chemical for thereby decomposing the organic chemical.