Abstract: Abstract: Solvent extraction behavior of Pa with Di-iso-propyl-ketone (DIPK) in benzene Is studied by 233Pa as a tracer. The extraction efficiencies of protactinium are measured as a function of shaking time, concentrations of different acid, and extractant concentrations. The effect of F anion were also been investigated. The results show that DIPK is an excellent extractant for protactinium and DIPK/HCl system is suitable for the extraction of Pa.