Currently, fossil-derived crude oil is the major resource for the production of aromatic commodity chemicals. However, the use of fossil fuels resulting in environmental damages such as global warming and rising CO2 concentration in the atmosphere. One such alternative is lignocellulosic biomass-derived lignin, but the lignin is mainly considered a waste by-product stream in the paper, pulp, and 2G ethanol biorefineries and treated as a heat/power generation source for boilers. However, lignin is abundant and potential aromatic carbon feedstock on the planet earth. Hence, the demand for the production of biobased chemicals from lignin is increasing in biorefineries. Despite its recalcitrant nature and irregularity in lignin structure, many thermochemical strategies have been developed to depolymerize lignin to aromatic chemicals. The present chapter focuses on lignin’s depolymerization to aromatic chemicals using various thermochemical methods, including pyrolysis, hydrothermal liquefaction, solvolysis, reductive, and oxidation processes. The effect of lignin feedstock, catalyst type, and the reaction parameters, including reaction temperature, residence time, pressure, and the solvent medium, on the distribution of degraded lignin products, including low molecular weight monomers, oligomers, and solid char and possible mechanisms, was discussed. © 2022 Elsevier Inc. All rights reserved.