The thermal decomposition reaction of LDPE, iPP and LDPE/PP blends irradiated with accelerated electrons has been investigated with TGA and DSC. TGA showed only one degradation step at different temperatures according to the type and composition of the samples. LDPE exhibited the highest thermal stability compared with either iPP or LDPE/iPP blends; LDPE/iPP blends showed intermediate thermal stability. TMPTMA loading and irradiation enhanced the thermal stability of all samples. The obtained TGA data by the stimulation method illustrated that the compatibility between LDPE and iPP in their blends takes place during mixing and irradiation processes, where only one degradation step was observed in the experimental TGA data instead of two degradation stages that appeared in the arithmetic calculation curve of the blend. The melting temperature decreased for TMPTMA loaded LDPE, whereas irradiation and/or loading with TMPTMA did not change the melting temperature of iPP. LDPE/iPP (50/50wt%) showed a drop in melting temperature compared with the components. The glass transition temperatures increased as a result of modification either by TMPTMA loading or irradiation. (C) 2005 Elsevier B.V. All rights reserved.