My research addresses how cellulose in waste biomass was converted into biochemical products through hydrothermal liquefaction (HTL). In HTL experiments, aqueous product samples were collected at different reaction times, separated by vacuum filtration, and analyzed by High Performance Liquid Chromatography (HPLC). Exponentially Modified Gaussian (EMG) model was applied to fitting the HPLC curves of the standards under different concentrations. The EMG model corresponded well with each curve with mean percent error (MPE) values less than 3%. Overlapping HPLC signals were observed and resolved computationally using the superposition of EMG functions. To simulate HTL reaction kinetics, various reaction pathway schemes were proposed based on the experimental findings. Best-fit reaction kinetic parameters were derived from an optimization of the errors of reaction kinetic modeling. The reaction kinetics will help entrepreneurs and researchers optimally produce selective commodity biochemical from waste biomass to provide alternatives to the petrochemical industry.