The potential of Polyalthia longifolia (PL) seed powder to adsorb methylene blue (MB) from aqueous solution has been investigated through batch experiments. The MB adsorption was found to be dependent on adsorbent dose, contact time, initial MB concentration and temperature. The time required to obtain the maximum adsorption was found to be two hours at 298 K. The equilibrium data were described by Freundlich, Langmuir and Tempkin isotherm models. The Langmuir isotherm model was well fitted and maximum adsorption capacity was found to be 9.19 mg/g at 298 K.The kinetic processes of MB adsorption on PL seed powder were described by applying pseudofirst order and pseudo-second order equation. The adsorption process obeyed pseudo-second order kinetic equation. Thermodynamic parameters such as standard enthalpy (ΔH 0), standard entropy (ΔS 0) and standard free energy (ΔG 0) were evaluated.The adsorption interaction was found to be spontaneous and exothermic in nature. The adsorption capacity of Polyalthia longifolia seed powder as found from the result suggest a non-conventional and efficient biosorbent for the removal of MB from aqueous solution and can be used for the development of clean and cheap technology for effluent treatment.