The extraction behavior of Eu(III) from nitric and hydrochloric acid By solutions of CMPO with and without TBP has been studied using mesitylene and dodecane as diluents. Compared to CMPO alone, the CMPO-TBP mixture shows a slight enhancement in the extraction of Eu(III) from nitric acid above 2M and lower DEu’ s from low acidity. The distribution ratios measured for Eu(III) between HN03 and CMPO-TBP in dodecane are higher than the corresponding values in mesitylene.Extractant dependency studies in the presence and absence of TBP show that at low HN03 concentrations, the extractant dependency curve obtained in the presence of TBP lies below the curve obtained in the absence of TBP. At high acidity, the opposite is observed. The extraction of Eu(III) from hydrochloric acid by CMPO-TBP in dodecane is much lower than from nitric acid. A comparison between CMPO and D2EHPA for Eu(III) extraction has been carried out.