Abstract: Catalytic lignin depolymerization (CCLD) for liquid fuels and phenolic monomers was investigated over various supports including clays (e.g., sepiolite (SEP), attapulgite (ATP), and montmorillonite (MTM)), and oxides (e.g., Al₂O₃ and SiO₂) as well as their supported Mo-based catalysts under supercritical ethanol. The characterization results demonstrated that different supports with diverse structural properties could affect the textural structures, surface Mo⁵⁺ content, and acid sites distribution. Clay-based supports had more strong acid sites as compared with Al₂O₃ and SiO₂, which went against the production of lignin oil (LO) and led to form more solid products during CLD experiments. Meanwhile, the obtained petroleum ether-soluble product (PE_sp) in LO catalyzed by sole supports was mainly alkyl/alkoxy substituted phenols. Additionally, Mo species (especially Mo⁵⁺) significantly increased the yields of LO and PE_sp. Mo/SiO₂ had the highest surface Mo⁵⁺ species, showing the highest LO yield of 85.2%, in which the produced alkyl/alkoxy substituted phenols reached 450.3 mg/g_lignin. Among the clay-supported Mo catalysts, Mo/SEP presented superior LO (82.3%) and PE_sp (70.8%) yields and the generated substituted phenols reached 398.8 mg/g_lignin. This paper systematically reported the application of green and environmentally friendly clay-based materials in lignin conversion, which provides some key information for the development of clay catalysts for biomass conversion.