Extraction of Zn and Cr(III) with solvents containing (1) DEHPA, di-2-ethylhexyl phosphoric acid, (2) PC-88A, 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester, (3) Cyanex 272, bis(2,4,4-trimethylpentyl)phosphinic acid, and (4) Cyanex 302, bis(2,4,4-trimethylpentyl)thiophosphinic acid, was studied with a view to separately recovering the two metals from alloy electroplating wastewater. All solvents extracted Zn well. Extraction of Cr(III) required a higher pH and Cr(III) hydroxide precipitation placed an upper limit on the pH that could be used, which in turn limited the extraction percentage. Among the four extractants, DEHPA performed the best, achieving close to 100% extraction at 0.1 M. The extracted Cr(III) could not be completely stripped (back-extracted). By using ammoniated DEHPA, both the precipitation and incomplete stripping problems were averted. The different performances of the DEHPA and ammoniated DEHPA solvents were explained in terms of the different extracted Cr(III) species and the slow kinetics of reactions involving ligand displacement of the Cr(III) species. This explanation was supported by stoichiometric and UV-visible spectral data. A flow sheet based on Zn extraction with DEHPA and Cr(III) extraction with ammoniated DEHPA was developed for treatment of Zn-Cr(III) alloy electroplating wastewater. The flow sheet was tested in an automated mixer-settler solvent extraction system. The treated wastewater contained < 0.1 mg l(-1) Zn and < 1 mg l(-1) Cr(III), and the recovered metals were in good purity.