A previously reported cation exchange process for the recovery of Pu from sump water was studied in order to improve the procedure. The flowsheet calls for adjustment to 0.03M HNO/sub 3/, the addition of NH/sub 4/HSO/sub 3/ for Pu reduction, the addition of Al/sup 3 +/ to complex F/sup -/, followed by passage of the solution through a column of Dowex 50W, X-8 resin. Distribution coefficients were measured between the resin and synthetic sump solutions under a variety of possible simulated flowsheet conditions. By far the highest distribution coefficients were obtained with Pu(III) without the addition of Al. Results with Pu(IV) varied from borderline to unsatisfactory depending on conditions. It is concluded that the process will be satisfactory if the Al addition is eliminated. (JGB)