The Fe-treated calcium phosphate (Fe-TPO4) has been prepared with FeCl3 aqueous solution. The sorption of (MoO42-)-Mo-99 ions from aqueous solution using Fe-TPO4 as adsorbent is investigated by batch experiments. Experiments have been performed as a function of shaking time, pH, solute concentration and temperature and the experimental rate data are tested with the pseudo-second-order rate model. The adsorption data as a function of molybdate concentration obey the Freundlich isotherm. Thermodynamic parameters Delta H-0, Delta S-0 and Delta G(0) have been calculated with data of temperature studies. The positive value of Delta H-0 indicates that the adsorption of MoO42- ions on Fe-TPO4 is an endothermic process.