Abstract: Smokeless burnout of regenerative thermal oxidizer systems is accomplished by isolating the incineration system from the process flow and drawing fresh air into the heating regenerator at approximately one-fourth of the normal process flow. A purge/burnout fan is employed to induce flow through an idle regenerator drawing high temperature gas from the retention chamber through the idle regenerator. Gas is directed from the purge/burnout fan back into the retention chamber to oxidize contaminants which has been volatilized from the media in the third regenerator. The reduced flow rate of the system and maintaining flow through the regenerator being burned out while continuing to cycle the remaining regenerators as heating and cooling regenerators builds the temperature in the burnout regenerator until volatilization of all contaminants is achieved.