The slow pyrolysis of unsegregated municipal solid waste is studied in this work using thermogravimetry coupled with gas phase FTIR, differential scanning calorimetry, synchrotron-based infrared micro-spectroscopy and DRIFT-FTIR. The results obtained from these techniques are utilised to characterise the individual components and the binary and the ternary mixtures in the waste sample. The results reveal the effect of binary and ternary interactions on the profile and the quality of the volatiles produced during the pyrolysis process. The pyrolysis oil is characterised by comparing the ratios of alkanes-to-aromatics, aldehydes-to-acids, and the total quantity of acid produced in the vapours. The results indicate that rubber component of MSW when co-pyrolysed with biomass and plastic is expected to improve the stability of pyrolysis oil. To enhance the oil quality further, the ratio of biomass to plastic, as well as the ratio of poly-ethylene terephthalate to other plastic components should be reduced in the mixture. Moreover, the gas yields during pyrolysis of various combinations of MSW components at different temperatures are used to identify the temperature range for MSW pyrolysis accounting for the effect of interactions on the volatiles evolution. The major effect of these interactions is the delayed emission of aldehydes and aromatics. (C) 2019 Elsevier Ltd. All rights reserved.