The separation properties of the hydrocyclone and the centrifuge were compared with regard to applying the apparatus in the uranium extraction process. The product was applied as a comparative factor where is the average emulsion residence time inside the separator and ā is the acceleration calculated for the mean radius of the separator chamber. The values corresponding to typical operational conditions of centrifuges tested appeared to be significantly higher than those calculated for the hydrocyclone. Separation tests performed with the 1 N HNO3-30% tributyl phos-phate-Mepasine system gave negative results in the case of the hydrocyclone while the complete emulsion separation was attained in various centrifuges under conditions when 9 × 105 cm·s−1. The results obtained suggest that the ≥ product can be applied as the criterion of the satisfactory phase separation in the centrifugal apparatus.