Abstract: This invention relates to a method of purifying niobium containing an impurity having a significant diffusion rate above about 1000.degree. C. which comprises vapor depositing a film of yttrium (Y) upon the surface of the niobium to be purified in a vacuum greater than about 10.sup.-4 torr and at an elevated temperature above about 1000.degree. C. (preferably between about 1200.degree. C. and 1400.degree. C.) for a time sufficient to cause migration of impurities from the niobium and binding of the impurities by the yttrium metal. The process of the invention, in it presently preferred embodiment can be accomplished by bringing the surface of shaped niobium article into close proximity with the yttrium metal under the appropriate process conditions.