The effect of organic solvents based on carbon tetrachloride and trichloromethane, the type of anion and temperature on the interaction of europium (III) with 2,2`-dipyridyl (2,2`-Dipy) is studied by spectrophotometric methods. Features of electronic spectra of compounds are detected, the ratio of Eu (III): 2,2`-Dipy and stability constants of complex compounds are identified, changes in Gibbs energy, enthalpy and entropy in the process of the formation of complexes are calculated.

Key words: non-polar organic solvents, binary solvent, lanthanide compounds, complex formation, stability constants.