An ion-exchanger colorimetric method for the determination of zinc(II) with Zincon has been developed. Zinc in a water sample can be determined by sorption onto an anion-exchange resin from 2M chloride solution followed by transformation into a coloured complex with Zincon. With use of a 1-litre sample the sensitivity is 10 times greater than that for conventional colorimetry. Most metals, except cadmium(II), lead(II) and bismuth(III), do not interfere when present in up to 100 times the concentration of zinc. The zinc: Zincon ratio of the complex in the resin phase was found to be 1 : 1 by the molar ratio method.