Abstract: The specification discloses a process for the treatment of waste gas containing hydrogen chloride wherein the gas is at an elevated temperature in the range of from about 300.degree. F. to about 3000.degree. F. and is produced from the thermal decomposition of material contaminated with hazardous chlorinated organic compounds. The waste gas is contacted in a reaction unit with an alkaline brine solution under conditions such that hydrogen chloride in the waste gas reacts with the alkali to form a chloride salt and water. The heat of the gas evaporates water from the solution to maintain the salt concentration sufficiently high to cause the formation of salt crystals in the solution. The gas is conducted from the reaction unit following contact with the solution under conditions such that the gas includes water evaporated from the solution.