The thermal and catalytic degradation of acrylonitrile-butadiene-styrene copolymer (ABS) was performed at 400 degreesC in static nitrogen atmosphere, by semibatch operation. gamma -Fe2O3, an Fe3O4-C composite, and alpha -FeOOH were used as catalysts, in two contact modes: either mixed with the polymer or in contact with the volatile degradation products of ABS;. All iron oxides decrease the concentration of nitrogen (N) in ABS degradation;oil. Reactions in a flow-type reactor with 4-phenylbutyronitrile as model N-containing compound show that alpha -FeOOH is active at low temperatures (250-300 degreesC) in converting heavy N-containing compounds into light aliphatic nitriles. XRD analysis proved that during reaction alpha -FeOOH was transformed into Fe3O4 in several steps, with alpha -Fe2O3 as intermediary compound.