Acid-functionalized mesoporous carbons (AF-MPCs) have been synthesized and used as adsorbents for removal of an azo dye, Eriochrome Black-T (EBT), from aqueous solution. To generate acid surface functionalities, mesoporous carbons (MPCs) were treated with sulfuric acid. Characterization of the samples was analyzed by XRD, Raman spectra, N-2 adsorption-desorption, FE-TEM, TGA, and FT-IR studies. The adsorption studies were carried out under various parameters, such as pH, adsorbent dosage, contact time, initial dye concentration solution temperature, and salt concentration. The results showed that the EBT adsorption onto samples was affected by the pH of solution; the maximum EBT ion adsorption took place at pH 1; and the adsorption uptake was increased with an increase in the initial dye concentration. Moreover, the mechanism of adsorption was investigated using kinetic, diffusion, and isotherm models. The best fit was obtained by the Langmuir model with high correlation coefficients (R-2 = 0.9463) with a maximum monolayer adsorption capacity of 117.0 mg.g(-1). The adsorbed anionic EBT dye molecules were eluted by ethanol solvent with the recovery percentage of 98%. Moreover, this study demonstrates that AF-MPCs can be successfully used as a low-cost adsorbent for the removal of EBT from aqueous solutions.