AbstractIn this paper, the photometric properties of the heteropolyacid ion‐associate Crystal Violet‐molybdophosphate in various media have been studied and its composition has been established as (C25H30N3)3· (PMo12O40) by means of spectrophotometry, elemental analysis and infrared absorption spectrophotometry. It has been proved that the photometric properties of the ion‐associate depend mainly upon the cation of the basic dye. We have also compared the suspension (or centrifugation) separation‐organic solvent dissolution method, the micelle solubilization method and the soluble polymer protectio