The extraction of zinc(II) and cadmium(II) from chloride media by mixtures of primary amine N1923 and 2-ethylhexyl phosphonic acid di-2-ethylhexyl ester (EH/DEHP, B) has been studied in the present paper. The mixtures have synergistic effects on zinc(II) at low levels of N1923 but antagonistic effects at high N1923 levels. However, synergistic effects are observed for the extraction of cadmium(II) at any proportion of the extractants. Zinc(II) is extracted as (RNH3-Cl)(2).ZnCl2.B, whereas cadmium(II) is extracted as (RNH3Cl)(4.5).CdCl2.B by the mixtures, instead of (RNH3Cl)(3).MCl2 (M = Zn or Cd) by N1923 alone. Furthermore, the formation constants and thermodynamic functions were determined. The possibility of separating zinc(II) and cadmium(II) by these mixtures according to the synergistic or antagonistic effects was investigated.