A method for determining zirconium in plutonium-zirconium alloys was required as part of an investigation of alloys containing fissionable material, with possible use in nuclear reactors. Alloys of these two elements were brought into solution with a bisulfate fusion and the zirconium was separated by precipitation with p-bromomandelic acid. Determinations were completed by weighing the zirconium oxide obtained after ignition of the precipitate at 925 degree C. The precision of this recommended procedure was estimated in terms of the standard deviation for quadruplicate determinations, made with weight aliquots from dissolved alloy samples. The range for the standard deviation was 0.5 to 1.7 parts per thousand for samples from which aliquots each containing 9 to 15 mg of zirconium were selected. The complete recovery of zirconium from solutions of pure zirconyl chloride and plutonium trichloride was shown by the 95 percent confidence limits of 99.9 +- 0.3 percent for the average of four determinations, observed with samples containing 5 to12 mg of zirconium in the presence of 10 to 20 mg of plutonium. It was found the Mo, La, PU(III), and K2Cr2O7 do not interfere with zirconium determinations made according to the recommended procedures, but Pu(IV) does interfere slightly. It was …