Water-extractable organic C (WEOC) plays an important role in organic C loss and retention, but little is known about the effect of clayey soil addition to sandy soil on short-term sorption and release of WEOC with regard to clay soil rate and properties. Wheat straw-derived WEOC was added at 0, 403, 759, 1379, 2505 and 4831 mg kg(-1) to sandy soil alone or amended with two clayey soils: vertisol (high cation exchange capacity (CEC)) and solonetz (low CEC) at 10, 20 or 40% (w/w). After over-night shaking, the supernatant was decanted to determine sorption. Then, water was added followed by over-night shaking for determining desorption. In sand alone, net sorption (sorption with WEOC added-no WEOC added) was low and little affected by WEOC addition rate. With vertisol, net sorption increased with WEOC addition rate and was three- to tenfold higher than with sand alone and higher than with solonetz. With both clayey soils, net sorption differed among clay rates only at <= 1379 mg kg(-1) where it was about 30% higher with 40% vertisol and sixfold higher with 40% solonetz, compared to 10% clay soil. Net desorption differed little between sand alone and with solonetz, but it was up to twofold greater than with vertisol. Addition of clayey soils to a sandy soil increased short-term sorption of WEOC which was influenced by clay CEC and addition rate. However, the release of previously bound WEOC indicates that WEOC may be bound to clays only temporarily.