We report the design of an ultrahigh vacuum compatible vapor dosing system for organometallic compounds. A unique feature of this doser is the elimination of all metallic surfaces in order to reduce the reactivity of the organometallic molecules towards the doser walls. The vapors only come in contact with glass, Teflon, and Kalrez and the doser is heatable to temperatures of 150 °C. A novel modification to a commercial glass stopcock is described. These modified valves are used in the doser to seal the ultrahigh vacuum system from the organometallic sample compartment and have been shown to be able to allow the vacuum system to maintain ultrahigh vacuum conditions even when the sample compartment is vented to atmosphere. Spring‐loaded Teflon seals are used to seal the valve shaft against the glass wall thereby maintaining ultrahigh vacuum conditions and a chemically inert surface for the organometallic compounds. A further modification to these commercial valves is described allowing it to function as the sample compartment for the organometallic material. This compartment features a heatable reservoir, vacuum seals to ultrahigh vacuum levels, and a rapid exchange design to permit the interchange of dosing materials. ©1995 American Institute of Physics.