Thermal oxidation and photodegradation of alkyl, alkyl-aromatic and synthetic resins were investigated. The ageing temperatures were selected in the range 150-200 degreesC. The progress in chemical degradation depicted by changes in characteristic absorption bands was monitored by spectral techniques. Differential scanning calorimetry investigation and chemical determination of hydroperoxide content were also performed. Based on the experimental data the main kinetic characteristics of the degradation processes were calculated. A discussion on the mechanistic aspects concerning thermal and photochemical ageing of the resins studied is also presented. (C) 2004 Elsevier B.V. All rights reserved.