SUMMARYEquilibrium competitive‐adsorption coefficients derived from the application of the multi‐component Freundlich‐type Sheindorf‐Rebhun‐Sheintuch (SRS) equation appeared to have a soil‐specific, quasi‐thermodynamic basis. Using three soils, single‐solute adsorption isotherms at 288, 298, and 308 K were constructed with arsenate, phosphate, and molybdate. A Clausius‐Clapeyron‐type equation was used to estimate apparent isosteric heats of adsorption values (qiso). The adsorption of the three anions was characterized by differentqisovalues, and was generally in the order of H2PO4‐>H2AsO4‐>MoO42‐. The magnitudes of the SRS competitive coefficients derived from binary‐solute mixtures were in agreement with the distributions of the heats of adsorption of the individual anion‐soil systems. Higher competitive coefficients, indicating the preferential adsorption of solute i in a binary‐solute mixture containing solutes i and j, tended to associate with higherqisovalues for solute i relative to solute j. However, theqisovalues for the adsorption of molybdate by one soil underestimated the extent of competitive interactions