Processing contaminated water containing volatile or/and semi-volatile compounds via flash evaporation. Method and system include: superheating contaminated water (via a superheating unit), for forming superheated contaminated water having a temperature equal to or higher than a predetermined threshold temperature; flash evaporating the superheated contaminated water (via a flash evaporation unit), for forming superheated contaminated steam; and thermally oxidizing the superheated contaminated steam (via a thermal oxidation unit), so as to thermally oxidize the volatile compounds contained therein, and form thermal oxidation gas/vapor products. Optionally, further includes integrated configuration and operation of a process control/data-information processing unit, and a heat recycling unit. Results in obtaining high yields and high energy efficiencies for removal of volatile compounds from contaminated water. Particularly applicable for processing water contaminated with volatile organic compounds (VOCs) or/and semi-volatile organic compounds (SVOCs), and volatile or/and semi-volatile inorganic compounds.