SUMMARYThe sorption of inorganic anions by hydrous ferric oxide gel (Fe gel) from 10−1M NaClO4at pH 6.5 decreased in the order: orthophosphate (H2PO4)>arsenate (H2AsO4) = selenite (HseO3)>silicate (H4SiO4)>molybdate (MoO24−)>sulphate (SO24−)>selenate(SeO24−)>chloride (Cl−) = nitrate (NO−3). When each anion was added to Fe gel with an equimolar quantity of H2PO−4, there was no detectable effect of SO24−, SeO24−, Cl−, and NO−3on the amount of H2PO−4sorbed. Other anions depressed H2PO4sorption in the order H2AsO4>HseO3>H4SiO4>MoO24. At the lowest level of anion addition (500 mmol kg−1), H2PO4sorption was depressed by no more than 6% of the sorption level in the absence of a competing anion. In contrast, at the highest level of anion addition (1700 mmol kg‐1of each), H2AsO4decreased H2PO4sorption by 44%. The sorption of SO4−was completely eliminated when this anion was added with equimolar amounts of H2PO4. The ability of anions to compete with H2PO4for sorption sites could not be explained solely by the results obtained for the sorption of each anion alone. Thus, H2AsO4was more competitive than H2PO4when added together, even though more H2PO4than H2AsO4was sorbed when each anion was added alone. Although H2PO4was sorbed in larger amounts, there is no evidence to suggest that H2PO4. H2AsO4, and HseO3w