A procedure is described for the growth of large single crystals of gallium phosphide. A vertical Bridgman apparatus is employed with a controlled phosphorus pressure source to maintain stoichiometric conditions during freezing. The high phosphorus pressure is contained by the use of heavy-walled quartz in the low temperature zone, and by permitting the thin-walled quartz in the hot zone to soften and expand out against a graphite support tube. Crystals doped with both zinc and tellurium have been prepared. The electrical properties of these and “undoped” crystals are presented. © 1968, The Electrochemical Society, Inc. All rights reserved.