Electrode potential and polarographic studies have been made on solutions of zirconium and hafnium ions in molten eutectic at 450°–550°C. Anodic dissolution of Zr at 450°C yielded Zr(IV), but at 550°C, chiefly Zr(II). Only Hf (IV) was observed over this range. Apparent standard electrode potentials were (mole fraction scale, Pt(II)/Pt(0) reference)