The performance of six chelating reagents [ethylenediamine-N,N,N′,N′-tetraacetic acid (EDTA); trans-1,2-cyclohexanediamine-N,N,N′,N′-tetraacetic acid (CDTA); N′-(2-hydroxyethyl)ethylenediamine-N,N,N′-triacetic acid (HEDTA); triethylenetetraamine-N,N,N′,N″,N‴,N‴-hexaacetic acid (TTHA); diethylenetriamine-N,N,N′,N″,N‴-pentaacetic acid (DTPA); and citrate] has been studied for masking zirconium(IV) in the determination of fluoride with an ion-selective electrode. Citrate was not suitable because it produced a prolonged electrode response. Of the aminopolycarboxylates, DTPA has a much greater masking ability than the others. Using DTPA at pH 5–6, fluoride was successfully determined at a concentration of 1 × 10^–5 mol dm^–3 in the presence of up to 4 × 10^–6 mol dm^–3 zirconium(IV). The proposed method was applied to the analysis of a number of zirconium(IV) fluoride compounds and ZrF₄-based glasses after fusion with sodium carbonate.