Some intensely coloured Cu(II)–L1–2′,7′-dichlorofluorescein ternary complexes were studied. The absorbance characteristics for these ternary complexes were determined. The molar ratio for these complexes is Cu:L1:L2 = 1:2:1 and the formula [Cu(L1)2]2+•[Cl2FlCOO−]− is proposed. The effect of substituent groups of the L1 and L2 ligands on the complexing activity with copper(II) was studied. The interference of some cations and anions in the determination of the Cu(II) by the developed methods was examined. Highly sensitive and selective methods are proposed for the spectrophotometric determination of copper(II) in limestone and copper alloys.