A solid-phase extraction (SPE) method, using silica bonded with aminopropyl groups, was developed to separate highly complex mixtures of degradation products into three fractions. The SPE allowed the subsequent GC-MS identification of nearly 140 thermo-oxidation products of starch-based polymer blends, consisting of 70% starch and either ethylene maleic anhydride (EMA) or ethylene vinyl acetate maleic anhydride (EVAMA). It was thus possible to identify several homologous series of degradation products such as n-alkanes and 1-alkenes, 1-alcohols, 2-ketones, aldehydes, carboxylic acids and dicarboxylic acids. The homologous series of dicarboxylic acids ranged from butanedioic acid (C 4) to nonadecanedionic acid (C 19) and was for the first time identified in thermo-oxidized starch-based blends with polyethylene (PE). Hydrocarbons of even carbon number were formed to a larger extent than those with an uneven carbon number in the starch-EMA blend and the ratio n-alkane to 1-alkene increased (i.e. relatively more alkane is formed) under more severe thermo-oxidation conditions. The same phenomenon was not observed in the starch-EVAMA blend. Formic acid, acetic acid and γ-butyrolactone were the most predominant degradation products in both materials. Typical starch degradation products were difficult to resolve but we identified 2-hexanone, formic acid and acetic acid, which also have been reported previously to be degradation products of starch. The molecular mass measurements showed that the starch-EVAMA blend starts to degrade earlier than the starch-EMA, but on the other hand, at a lower rate. A good correlation between the decrease in M n and the amount of degradation products formed was observed. A higher degree of cross-linking occurred in the starch-EVAMA blend in comparison with the starch-EMA blend and, in parallel, qualitatively and quantitatively more degradation products are formed in the starch-EMA blend.