Abstract: A method and apparatus for ultrapurification of indium and other metals having a wide liquid range and low vapor pressure. The purification method involves producing a small-diameter stream of liquified metal, directing this stream along a predetermined path while subjecting it to a high vacuum and heating it to vaporize volatile impurities, then collecting and solidifying the purified stream. The method is optimally practiced in the ultrahigh vacuum and substantially zero gravity environment of outer space. Apparatus for practicing the method in outer space employs a containerless refining zone in which the stream of liquid metal being purified is directed along a path defined by edges of thin guides fabricated of material which is not substantially wetted by the liquid metal. Heating of the liquid metal stream is accomplished via RF coils surrounding the guides defining the stream path. Upon collection, the purified metal stream may be further subjected to a secondary refining process.