[en] Kinetics of extraction of lanthanides by solutions of di-(2-ethylhexyl)phosphoric acid in toluene was investigated by the method of diffusion cell with mixing. It was established that 20-30% of initially taken amount of Ln³⁺ was accumulated in the interphase film in 60 min after the begining of the experiment conducted under pH-static conditions. It was revealed that dependence of accumulation on time could be of extreme character under certain conditions. It is shown that basic salts formed during interaction of hydrolyzed forms of lanthanides with di-(2-ethylhexyl)phosphoric acid enter the composition of inetrphase film along with polymeric molecules