A rapid and simple general complexometric method was presented for the determination of lead, cadmium and thallium or mercury or arsenic(V) in laboratory synthesized mixtures similar to those of some ores, minerals and alloys of such metals. The precision and accuracy attainable in successive titrations of Pb²⁺, Cd²⁺ and Tl³⁺ or Hg²⁺ or AsO³⁻₄ (As⁵⁺) with 0.05 and/or 0.01 mol 1⁻¹ solutions of disodium ethylenediaminetetraacetate (Na₂EDTA) and standard Pb(NO₃)₂ of the same concentration using Bromo-Cresol Orange (BCO) as a new metallochromic indicator with visual endpoint indication were studied. For the analysis of a three component mixtures of the aforementioned ions, Tl³⁺ was at first directly titrated with Na₂EDTA at pH 0.5–1 (HNO₃) using BCO as indicator. At the thallium endpoint an excess of Na₂EDTA was added and the pH was adjusted at pH ∼ 4.8 using hexamine-HNO₃ buffer (solution A). The excess EDTA was back-titrated with standard solution of Pb(NO₃)₂. 1,10-Phenanthroline (1,10-phen) was added to release the EDTA combined with Cd²⁺, while thiosemicarbazide (TSC) was used to liberate the EDTA from the mercury-EDTA chelate. To determine AsO³⁻₄ ion in such type of mixtures the pH of (solution A) was raised to a value of 10 using ammonia buffer. Excess standard Mg²⁺ solution was added and the formed precipitate of MgNH₄AsO₄ was separated, dissolved and its magnesium content equivalent to AsO³⁻₄ was determined complexometrically using Eriochrome Black-T (EBT) indicator. The interference caused by different anions, cations and organic acids was investigated. A comparison of the indicators BCO and Xylenol Orange (XO) for successive titration of the studied metal ions was carried out. The proposed successive titration method was applied successfully to some real samples of ores, minerals and alloys of the studied metal ions and the results were satisfactory and agreed with those obtained by AAS.