Present study discusses the removal of heavy metal contaminants from an aqueous solution using orthophosphoric acid activated pumpkin seed shells derived activated carbon (PSS-AC). The activation was done by heating the mixture in an electrical furnace at 800 °C for 3 h. Adsorption experiments were carried out as a function of pH, contact time, initial Cu (II) and Cd (II) ion concentrations, adsorbent dosage and temperature of the solution for the metal ion removal. The equilibrium and kinetic studies data were fitted better for the Langmuir isotherm model and pseudo-second order model respectively. Thermodynamic parameter obtained for Cu (II) and Cd (II) ions adsorption suggests the reaction to be non-spontaneous, feasible; and endothermic between temperatures of 25 °C and 45 °C.