[en] A conceptual process flowsheet for preparation of U₃O₈ by precipitating uranyl formate monohydrate with excess formic acid and calcining it was developed and demonstrated on a laboratory scale. The product U₃O₈ has a particle size distribution apropriate for fabrication of U₃O₈-Al fuel by powder metallurgy. The U₃O₈ particles are crystalline, do not exceed 150 μm in diameter, and have a narrow particle size distribution with most particles within the range of 44 to 150 μm. A ten-fold decontamination of uranium from low-level fission products during uranyl formate precipitation was demonstrated. Minimal variations in U₃O₈ particle size distribution as a function of various uranyl formate precipitation conditions were observed. Preliminary tests demonstrated that calcination of uranyl formate monohydrate recovered from solution by evaporation to dryness did not produce U₃O₈ with the desired particle size distribution. Calcination of uranyl oxalate, uranous oxalate, or uranous formate also did not produce U₃O₈ with the appropriate particle size distribution