A batch method was used to investigate the uptake of heavy metal cations and anions by the compounds in the CaTiO 3 –CaFeO 2.5 system, in which a series of oxygen vacancies was systematically introduced into a perovskite structure as the x-value of Ca(Fe x Ti 1−x )O 3−x/2 was increased. Samples of CaTiO 3 , CaFe 0.1 Ti 0.9 O 2.95 , CaFe 0.5 Ti 0.5 O 2.75 , CaFe 0.67 Ti 0.33 O 2.67 and CaFeO 2.5 were prepared by solid mixing (SM), co-precipitation (CP) and gel evaporation (GE) methods. The resulting samples were calcined at temperatures between 400 and 1000°C. The target crystalline phases differed according to the preparation method, but in most cases were formed at 700–800°C. The Ni 2+ sorption isotherms of all the samples were fitted better by the Langmuir model than by the Freundlich model, while in the case of H 2 PO 4 − sorption isotherms, these were better fitted by the latter model. The uptake ability increased with increasing x value of the samples. The maximum values for the saturated sorption of Ni 2+ (Q 0 (Ni 2+ )=2.83mmol/g) and H 2 PO 4 − (K F (H 2 PO 4 − )=2.95mmol/g) were achieved for x=1 (i.e. CaFeO 2.5 ) sample.