Abstract: An integrated oxidation-reduction process whereby a thermal oxidation zone and a NOx reduction zone are incorporated into a single device. A thermal oxidation and catalytic reduction system having a multi-spiral, heat recuperative configuration and including a lean NOx catalytic section disposed in the low-temperature regions is disclosed, as is a corresponding method. The catalyst may be disposed on the oxidizer walls or on a matrix of porous inert media disposed in the spiral passages of the oxidizer. A film-injection technique to selectively provide reactants to the catalyst surface is also disclosed. The catalyst may be limited to a concave portion of a sidewall to diminish boundary layer separation of the reactants.