The extraction of Eu(III) has been carried out from a 1 M (H,Na)Clo4solution into different organic solvents at constant total concentration (6.67 × 10−3M) of the extractant, di-n-butyl-ethane-(l,2)-diphosphonic acid (H2B2-EDP). The distribution coefficient of Eu(III) is influenced quite appreciably by the nature of the organic solvent. We observe that the distribution coefficient can vary by a factor of 106for two solvents such as chloroform and ieo-octane. The experimental results are compared with those of Dréze1, who used di-n-butyl-phosphoric acid (HDBP) for the extraction of Eu(lII) into different organic solvents. If we assume that H2-B2-EDP remains monomer for a total concentration of 6.67 × 10−3M in the solvents used2, then we may conclude that the extraction of Eu(III) by the associated HDBP or the monomer H2B2EDP is influenced in the same manner in the solvents used.