Normal butylamine compounds are proposed as new solvent-washing reagents. The washing behaviors of plutonium, zirconium, ruthenium, and di-n-butyl phosphoric acid (HDBP) are examined in a new solvent-washing process with n-butylamine oxalate and n-butylamine bicarbonate. The experimental data show that pH condition has a significant influence on the effectiveness of the washing. The oxalate effectively washed plutonium and zirconium in low pH condition by making oxalate complexes. The oxalate and bicarbonate washed plutonium, zirconium, and ruthenium in high pH condition by replacing a nitrate ion with a hydroxide ion and HDBP by dissociation with the hydroxide ion.