This paper presents the results of the preparation of di(2-ethylhexyl)phosphoric acid (D(2)EHPA)-impregnated Amberlite 200 resin and its application for the separation of Ni, V and Mo ions in sulfuric acid solution. The advantages of choosing this system are mainly due to the distinct metal ions extraction behavior of D(2)EHPA and Amberlite 200 resin. At low pH value, Amberlite 200 can sorb much higher amounts of Ni ion than V and Mo ions. D(2)EHPA can extract higher amounts of Mo ion than V and Ni ions at low pH value. The impregnation of D(2)EHPA into Amberlite 200 modifies the, metal ion sorption behavior of the resin. Three impregnation procedures were proposed to prepare the D(2)EHPA-impregnated resin. Surface modification with sodium dodecyl sulfate surfactant converts the hydrophilic surface of Amberlite 200 into hydrophobic nature, which improves the impregnation of D(2)EHPA. The highest amount of impregnated D(2)EHPA was about 0.26 g in 1.0 g of dry Amberlite 200 resin. In order to realize the effects of operation parameters on impregnation process, the characteristic properties of Amberlite 200 were investigated using the Brunauer-Emmett-Teller (BET) method and ESCA (electron spectroscopy for chemical analysis) to interpret the possible mechanism of impregnation. The sorption of Ni ion on D(2)EHPA-impregnated resin reduces to 33% of that on non-modified resin. The sorptions of Mo and V ions, however, increase by about nine and four times compared to those on non-modified resin, respectively. The results of selective extraction of mixed ion solution further demonstrate the feasibility of using D(2)EHPA-impregnated Amberlite 200 resin for the separation of mixed Ni, V and Mo ions. (C) 2003 Elsevier B.V. All rights reserved.