The liquid membrane separation of zinc, cadmium and nickel with a series of substituted 4-acyl-5-pyrazolones and homologous beta-diketones is reported. Acylpyrazolones enable a quicker metal separation than corresponding beta-diketones. Branched substituents hinder the permeation, observable especially with beta-diketones because of their lower acidity. Acylpyrazolones show higher permeation, but beta-diketones have a better selectivity for the separation of zinc, cadmium and nickel. The permeation is disturbed by higher concentrations of ammonia.