The valorization of the plastic part from waste electric and electronic equipment (WEEE) is of significant importance for the upcycling of this waste stream with pyrolysis proposed as an appropriate, environmentally friendly, thermo-chemical recycling technique. The subject of this study is to investigate the distribution of the products obtained after the addition of certain catalysts in the pyrolysis of polymer blends with a composition similar to that of plastics in WEEE. Specifically, blends of acrylonitrile-butadiene-styrene (ABS), high impact polystyrene (HIPS), polycarbonate (PC), polypropylene (PP) and poly(vinyl chloride) (PVC) were examined in experiments taking place in a lab scale pyrolyser coupled with gas chromatography/mass spectrometry (Py-GC/MS) for the on-line recording of the products obtained. Six different catalysts (CaO, γ-Al2O3, Fe2O3, ZSM-5, Silicalite, Al-MCM41) were used and the optimum pyrolysis temperatures were selected for each system based on evolved gas analysis. The results from catalytic cracking were compared and evaluated in terms of the number of compounds produced, the ratio between aromatic and aliphatic products, and the intensity of the peaks. It was found that the best choice for the decomposition of ABS is Fe2O3 and for HIPS the Al-MCM41. γ-Al2O3 affects PC degradation and CaO exhibits specific selectivity to this polymer. Pyrolysis of blends results in the production of a mixture of hydrocarbons together with other aliphatic and aromatic compounds. Polymer blends including chlorinated compounds such as PVC start degrading at relatively low temperatures, slightly over 200 °C. Degradation occurs in two steps with peaks around 300 and 465 °C, respectively. The first is attributed to the removal of halogenated compounds and the second to the scission of the main carbon chain. PVC degradation produces chlorine radicals that affect the degradation mechanism. The presence of the catalysts did not significantly change the temperatures of degradation. However, they do change the type of the products obtained. Pyrolysis of the styrenic polymers, i.e. ABS or HIPS resulted in mainly aromatic compounds with one, two or even three aromatic rings, whereas PC results in several phenols. CaO is proposed as the best choice for catalytic cracking of Blend A, whereas Silicalite should be considered for Blend B since it leads in the production of more aromatic compounds compared to conventional pyrolysis.