Cesium, coprecipitated with copper ferrocyanide, can be readily removed from radioactive process waste water using sodium lauryl sulphate (NaLS), cetyl trimethyl ammonium bromide (CTAB) or gelatin (Gl) as collector. In addition to the effect of the collector type on the percentage removal and volume reduction, the effects of the pH of three distinct Cu 2 + : Fe(CN)J ~ ratios and of different ageing periods of the cesium-copper ferrocyanide-water systems have been established. With NaLS, CTAB and Gl successful removals could be achieved in the pH ranges 3-7.5, 5.0-10.5 and 5.5-9.0 respectively. The results are discussed in terms of the ionization of the active groups of the collectors and of the electrical state of the precipitate.