An explosive vapor generator which produces transient "clouds" of explosive vapors for use in the evaluation of commercial explosive vapor detection systems has been developed based on a capillary gas chromatograph. The design of the vapor generator replaces a flame ionization detector on the gas chromatograph with an effluent heater system to provide a cloud of explosive vapor while preventing condensation onto the walls of the capillary column. This vapor source has been successfully used to produce vapors of dinitrotoluene (DNT), trinitrotoluene (TNT), and 1,3,5-trinitro-1,3,5- triazacyclohexane (RDX). The chemical composition of the output was confirmed by both ion mobility spectrometry, and quadrupole mass spectrometry. Adsorptive effects of TNT and RDX were studied in order to optimize the injection parameters, achieving detection limits three orders of magnitude lower than previously reported. The quantitative output of the system was verified using thermal tube desorption gas chromatography. / Ph. D.