Abstract: The high-purity acid hydrotropic lignin(AHL) was isolated from poplar wood followed by CO₂ assisted hydrothermal pretreatment and p-toluenesulfonic acid solution treatment. Then AHL was used as a precursor to prepared activated carbon of AHL-AC-H₃PO₄ and AHL-AC-KOH with well-developed pore structure through H₃PO₄ and KOH method, respectively. The structure of activated carbon was characterized through various techniques, and its electrochemical performance as an electrode material for supercapacitor was studied and compared. The structure characterization results indicated that the specific surface areas of AHL-AC-H₃PO₄ and AHL-AC-KOH were 2 490 and 3 344 m²/g, and the pore volume were 1.24 and 1.74 cm³/g, respectively. The characterization results of electrochemical performance analysis showed that as the current density increased from 0.5 A/g to 10 A/g, the specific capacitance of AHL-AC-H₃PO₄ decreased from 241.24 F/g to 83.95 F/g, and the capacitance retention rate was only 34.80%. The specific capacitance of AHL-AC-KOH decreased from 269.19 F/g to 229.76 F/g, with the capacitance retention rate of 85.35%. The charge/discharge behavior reversibility and rate performance of AHL-AC-H₃PO₄ were poor, and the resistance was large. AHL-AC-KOH had typical electric double layer capacitance and Faraday fast redox reaction characteristics, exhibited highly reversible charge/discharge ability, and had good rate capability and low resistance.