Polypropylene (PP) is the 2nd most used plastic globally, after polyethylene. Pyrolysis is a chemical recycling method used for plastic waste management, which involves heating plastic waste to temperatures of 300 – 800 ̊C in the absence of oxygen and ideally generates useful condensable and non-condensable products. Pyrolysis of PP in the presence of a catalyst has been shown to produce a number of valuable hydrocarbon products. Heterogenous aluminosilicate catalysts have been shown to increase the rate of plastic degradation during pyrolysis, facilitating degradation at lower temperatures. They also alter the selectivity of the pyrolysis products observed. Zeolites are aluminosilicate catalysts made up of a network of tetrahedral SiO4 and AlO4- units, connected through their oxygen atoms. Zeolites are known to effectively catalyse plastic pyrolysis by partaking in reactions with the plastic polymer at their surface acid sites, which are generated when H+ is used as the AlO4- counterion. A micro-mesoporous aluminosilicate catalyst was prepared using a facile hydrothermal modification of a hydrogen Y-zeolite seed. Mesopores were introduced using cetyltrimethylammonium bromide as a templating species, and their generation was confirmed using N2 physisorption. Transmission electron microscopy identified the formation of mesopores throughout the catalyst and also showed the presence of crystalline and amorphous phases in the material. Powder x-ray diffraction also confirmed the presence of the crystalline phase. Ammonia temperature programmed desorption was used to analyse the Bronsted acid sites in the catalyst and compare their properties to the acid sites in the zeolite seeds prior to the addition of mesopores. The performance of the micro-mesoporous aluminosilicate catalyst in the cracking of PP was investigated using thermogravimetric analysis and within a lab-scale pyrolysis reactor. The pyrolysis products were analysed using Fourier-transform infrared spectroscopy, gas chromatography, and gas chromatography with mass spectrometry.