Arsenic is an element of concern, as it is widely distributed in the environment and poses a great threat to the health of humans and other living beings. The present study investigates the uptake of arsenite (As(III)) and arsenate (As(V)) ions from aqueous solution using low-cost Polyalthia longifolia leaf powder (PLP). The low-cost adsorbent was characterized by FTIR and SEM-EDX measurements. Adsorption experiments were carried out, with contact time, pH, adsorbent amount, the concentration of As(III) and As(V) and co-existing anions (PO 4 3− and BO 3 3−) as the variables. Maximum adsorption of As(III) and As(V) was found at pH 7.5 and 3.0, respectively. The presence of PO 4 3− and BO 3 3− was found to be sufficient for the uptake of As(III) and As(V), respectively. Adsorption of both As(III) and As(V) on PLP was found to follow the pseudo-second-order kinetic model. Freundlich, Langmuir, and Temkin models of adsorption were tested for adsorption of As(III) and As(V) on PLP, and the results indicated that adsorption data closely followed the Langmuir model. The maximum adsorption capacity for As(III) and As(V) was 1.76 mg g −1 and 1.87 mg g −1 , respectively, under the experimental conditions. Thermodynamic analysis showed that the process of adsorption of both As(III) and As(V) on PLP was spontaneous and exothermic with decreasing degrees of freedom. The results indicated that PLP-As(III) and PLP-As(V) interaction equilibria were efficient and therefore could be explored for practical applications.