Abstract: The surface of a hierarchical porous carbon aerogel (HPCA-1) was modified with nitric acid to obtain mHPCA-1. Acid fuchsin (AF) adsorption on these carbon aerogels in water was studied. Results indicate that the acid modification has trivial effects on the morphology and pore structure, but obviously increases the number of surface oxygen-containing groups. The isothermal adsorption of AF on these modified carbon aerogels is monomolecular layer adsorption, and can be well described by the Langmuir equation. The maximum adsorption capacity on mHPCA-1 reaches 191.57 mg·g^-1, which is much higher than that on HPCA-1 (120.92 mg·g^-1). The adsorption kinetics can be well described by a first-order kinetic equation and the kinetic constant can be increased by the acid modification.