AbstractZirconium (IV) ions form violet red complex with 4,5‐dihydroxyfluorescein in fairly strong mineral acid medium. The reagent has been successfully applied as a metal indicator in the direct EDTA titration of zirconium.The complex formed by 4,5‐dihydroxyfluorescein and zirconium ions has been studied spectrophotometrically in 0.1MHCl solution. It is found that when an excess of metal ion is present, a violet red colored complex with metal‐ligand ratio of 1:1, (MR) is formed and when an excess of 4,5‐dihydroxyfluorescein is present a 1:2 complex (MR2) may be predominant. The 1:1 complex has maximum absorption at 510mμ and the 1:2 complex has very low solubility and tends to precipitate out from the solution. Job's method, log‐ratio method and gravimetric method were used to establish the composition of complexes. The apparent stability constant of the 1:1 complex is found to be logKh= 4.46 orKh= 2.9