The mechanism for the electrodeposition of coherent deposits of niobium from a molten fluoride electrolyte has been studied by means of chronopotentiometry and compared with that of tantalum. The reduction of the pentavalent niobium in solution occurs in three steps: a reversible one‐electron step to the tetravalent state at −0.11v (referred to the Ni/Ni2+ electrode), a reversible three‐electron step to the monovalent state at −0.76v, and finally an irreversible one‐electron reduction to metal at −1.02v. However, the reaction interferes with coherent metal deposition from the pentavalent solutions, and consequently in order that coherent metal be produced at high efficiency the mean valence of the bath must be reduced to approximately four. In these circumstances the chronopotentiogram of a working bath shows two steps only: a three‐electron reduction, followed by the metal producing step . The diffusion coefficient of has been found to be and its activation energy for diffusion to be 8.75 kcal/mole. The diffusion coefficient of the tetravalent species is .