Cd2+ ions adsorption along with potentiometric titration studies were carried out on AlPO4 as a function of pH, temperature and activation. The well-known Gaines-Thomas equation was found applicable and the dissociation constants (pKa) showed an increase with activation indicating a decrease in the surface acidity of AlPO4. Cd2+ ions adsorption was found to increase with pH, temperature and activation of the solid. The Freundlich equation was found applicable to the sorption data. Stoichiometry of Cd2+ to H+ of the exchange (X) and equilibrium constant K values were evaluated. The exchange stoichiometry was found to decrease while the equilibrium constant values increased with activation of the AlPO4 indicating a change in the mechanism of the process from ion exchange to chemisorption. FTIR studies were carried out for determination of the mechanism of the uptake by the solid.