Previous studies by Black and Blomquist on the degradative failure of polymer–metal adhesive bonds have shown that composite failure depends largely on the type of metal substrate employed. In the work reported herein, metal powders of high surface area have been employed to maximize the metal–polymer interface. The composite systems studied consisted for aluminum and iron with polycondensates of bisphenol A–diglycidyl ether, phenol–formaldehyde and poly-2,2′-(m-phenylene)-5,5′-bibenimidazole. The composites were prepared in the absence of air and thermally degraded in a time-of-flight mass spectrometer while the degradation products were continuously monitored from mass 1 to 200. In the polymer and polymer–metal systems investigated, iron accelerated the decomposition of all polymers studied. This was determined by plotting m/e against degradation temperature for the more common mass peaks such as hydrogen and carbon monoxide for the carbon–hydrogen–oxygen-containing polymer and hydrogen cyanide and ammonia for the carbon–hydrogen–nitrogen-containing polymer. This technique offers promise in determining the nature of the interface as well as the effect of the interface on polymer degradation.