The extraction of Zn(II), Cu(II) and Cd(TI) from nitrate solutions by impregnated resins containing mixtures of di(2-ethylhexyl)phosphoric acid (DEHPA) and tri-n-octyl-phosphine oxide (TOPO) have been studied. Impregnated resins containing TOPO and mixtures of DEHPA and TOPO have been prepared by direct adsorption of both extractants into macroporous supports, Amberlite XAD2. The adsorption of DEHPA and TOPO molecules on the macroporous support is shown by FTIR spectroscopy to be result of only weak extractant-support interactions. The distribution coefficients of Zn(II), Cu(II) and Cd(II) were determined as a function of pH and extractant concentration (DEHPA, TOPO) in the resin phase and the data were analyzed graphically using the slope analysis method in terms of synergistic effect. Analysis of the results showed that the extraction of these metal ions can be explained assuming the formation of metal complexes in the resin phase with a general composition MLp(NO3)(t)S-s(HL)(q) where p, t, s, q take values depending on the metal and the extractant concentration ratio in the resin phase ([HL](r)/[S](r)).