Abstract: A process for treating a cyanide and cyanate-containing aqueous influent such as a wastewater stream is provided. A two-stage method is included for destroying a cyanide-containing influent which comprises;(a) introducing said cyanide-containing influent into a first ozone-contacting zone;(b) contacting said influent in said first zone with a second ozone-containing gas, at least a portion of said second ozone-containing gas comprising a first ozone-depleted gas withdrawn from a second contact zone to form a first cyanide-depleted effluent and a second ozone-depleted gas;(c) introducing said first cyanide-depleted effluent into a second ozone-contacting zone;(d) contacting said effluent in said second zone with a first ozone-containing gas to form a second cyanide-depleted effluent and a first ozone-depleted gas;(e) withdrawing said first ozone-depleted gas from said second contact zone; and(f) withdrawing said second cyanide-depleted effluent from said second zone.