Limited research exists on the effect of oxygen on the species production during the controlled surface area pyrolytic decomposition of polypropylene. In this study, the pyrolytic decomposition of polypropylene was conducted in 0% O2, 5% O2, and 15% O2. The pyrolyzate produced during the experiments was analyzed using three methods. First, a custom tube-furnace reactor, auto-sampling system, and unique sample boat were developed to pyrolyze, collect, and deliver pyrolyzate to a GC-BID/MS for species identification and quantification. Data collected were converted to rates of production and mass evolved for individual species identified. Second, using the same tube-furnace reactor pyrolyzate was sent directly to a stack of IR and FID analyzers to measure O2, CO, CO2, and total hydrocarbon production. This data was converted and used to compare with and verify the data from the GC-BID analysis. Thermogravimetric analysis was used as a third technique to measure the mass loss of the polypropylene under the three O2 scenarios. For all three analytical methods, the effect of O2 was studied and was found to have a profound effect on species evolution and the temperature at which the reactions initiated.