The solid complex Eu(III)−bathophenanthroline was synthesized and characterized by elemental analysis, IR spectra, and thermal analysis. The interaction of the Eu(III)−bathophenanthroline solid complex with calf-thymus DNA has been investigated by fluorescence and electrochemical methods including cyclic voltammetery and differential pulse polarography on a glassy carbon electrode. The formation of binary and ternary complexes of Eu(III) with nucleotides guanosine 5′- monophosphate (5′-GMP), adenosine 5′-monophosphate (5′-AMP), inosine 5′-monophosphate (5′-IMP), cytidine 5′-monophosphate (5′-CMP), or N-acetylamino acids (N-acetylaspartic acid, N-acetylhistidine, and N-acetylhistamine), and bathophenanthroline (BPhen) has been studied potentiometrically at (25.0 ± 0.1) °C and an ionic strength of I = 0.1 mol·dm−3 (KNO3) in 1.8 % v/v ethanol−water mixture solvent. The formation of the normal and protonated binary and ternary complexes is inferred from the corresponding titration curves. The experimental con...