The synergistic extraction of zinc and cadmium (M2*) from sulphate, nitrate and perchlorate media with mixtures of 1-phenyl-3-methyl-4-benzoylpyra2ol-5-ol (HL) and n-dodecylammoniura salts (DDAH*,X−) in toluene has been studied. In sulphate medium, the lipophilic ammonium pyrazololate (DDAK*L−) is the predominating ammonium species : the synergy observed can be considered as the addition of (DDAH*,L−) on HL2perchlorate and nitrate media, the amphiphilic ammonium salts {DDAH*, CIO4−) and (DDAH+N03−) predominate, leading to the formation of an aqueous emulsion in equilibrium with a clear organic phase. Metal distribution curves show that the formation of the lipophilic synergistic species (DDAH+ML2−) results from a X−/ML3−exchange in the interfacial region between the aqueous and the organic phase. The addition of n-octanol or 4-nonylphenol in the organic phase turns the emulsion into a micro-emulsion whereas the substitution of toluene by chloroform largely decreases the emulsion stability.