Polymers have inherently high WC ratios, making liquefaction of waste plastics into liquid fuel feedstocks, a potentially viable commercial process. The objective of this study is to characterize the thermal degradation of polymers during hydrogenation. LDPE was studied due to its simple structure. Isothermal and non-isothermal TGA were used to obtain degradation kinetics. Systems of homopolymer, polymer mixtures, and solvent-swollen polymer were studied. The significant variables for liquefaction are pressure, temperature, and time. Product oil viscosity depends on hydrogen pressure. GPC analyses suggest that lower molecular weight polymer degrades at higher rates. Crystallinity increased in the THF and pentanes insolubles as compared to the original LDPE.