In recent months, relatively large quantities of neptunium-237 have been recovered from Hanford irradiated uranium. The over-all recovery process consisted of 1) isolation from Purex plant solutions by solvent extraction, to yield an impure neptunium nitrate solution contaminated principally with uranium, plutonium, and fission products (2) purification by anion exchange 3) precipitation of neptunium (IV) oxalate; and 4) calcination of the oxalate to yield neptunium (IV) oxide, NpO2. This paper describes the oxalate precipitation process investigations and results.