Sorption of pentavalent oxyanions P(V), As(V), and Sb(V) was studied on goethite and hematite prepared by its thermal transformation. The surface properties of goethite and products of its thermal modification at different temperatures were studied by BET method, FT-IR, XRD, and DTA-TGA. Amounts of immobilized ions reached their maxima on sorbent prepared at 250 degrees C. Changes of the specific surface area (32.5m(2).g(-1) at 150 degrees C, 82.3m(2).g(-1) at 250 degrees C and 34.8m(2).g(-1) at 350 degrees C) during the thermal transformation at different temperatures were observed. Further analysis confirmed the complete transformation of goethite to hematite at temperatures 200-250 degrees C accompanied with the disappearance of hydroxyl absorption bands at approximate to 800 and approximate to 900cm(-1) in FT-IR spectrum and significant loss of weight observed on TGA curve. The study of adsorption isoterms revealed that antimony has higher affinity for all studied sorbents.