The present work is an attempt to correlate the composition and some physico-chemical properties of two-phase systems with the stationary phase retention in a coil planet centrifuge of J-type. Complex liquid systems containing an organic solvent (n-decane or chloroform), an extracting reagent (di-2-ethylhexylphosphoric acid, D2EHPA), water and a mineral salt (ammonium sulphate) are considered. The extractant additions in the organic phase and the salt additions in the aqueous phase lead to the change of the physicochemical properties (viscosity, density, interfacial tension) of the liquid system and affect, strongly, the stationary organic phase retention. The influence of the rotation speed on the stationary phase retention for systems based on D2EHPA in chloroform and (NH4)(2)SO4 in water has been also investigated.