Peanut shell-based activated carbon (PSAC) was used to study the removal of methylene blue (MB) dye from aqueous solution. Chemical agent of sodium hydroxide (NaOH) and gasification agent of carbon dioxide (CO2) were used to prepare PSAC via physicochemical activation. In batch studies, several effects namely, initial MB dye concentration, solution temperature, and solution pH were evaluated. Isotherm and kinetic study revealed that the adsorption system of MB-PSAC was fitted the finest by Freundlich and pseudo-second-order models, respectively. Thermodynamic studies certified that MB adsorption onto PSAC was physically controlled and was endothermic in nature.