The thermal degradation and mechanical properties of poly(ethylene terephthalate) (PET) blended with compounds like starch, cyanoethylated cellulose, cyanoethylated wood flour and polylactide was investigated. The thermal degradation of the blends was studied using thermogravimetry while the mechanical properties were determined by measurement of tensile properties and impact strength. The results indicated the possibility of interaction between PET with other components during thermal degradation while the mechanical properties showed a reduction by the addition of these components owing to improper adhesion. © 2005 Elsevier Ltd. All rights reserved.