The feasibility and effectiveness of a field deployable gas chromatograph/mass spectrometer (GC/MS) were examined. The GC/MS was transported to several field sites, where a general approach to operating the instrument in the field was developed. Following the initial field studies, the GC/MS was reengineered and reconstructed to be more appropriate for field use. The GC inlet was modified to allow for rapid sample processing and improved chromatographic resolution. The main unit was divided into two parts: GC/MS hardware and the computer. In addition, several heavy or bulky parts of the apparatus were replaced by equipment of lower mass. By incorporating novel weight and size reducing vacuum technology, the mass of the GC/MS was reduced by approximately 50%. The assembly and startup time of the portable GC/MS ranged from 30 to 60 minutes. At a parts vapor degreasing operation, the GC/MS successfully identified 1,1,1-trichloroethane (71556) in the air samples. The GC/MS was also used to measure the air concentrations of benzene (71432) associated with cleaning operations on petroleum hauling barges. The GC/MS was also applied to the assessment of a furniture stripping operation, where numerous solvents were utilized. Prior to sampling and analysis, standard runs of the major solvents were made, permitting the simultaneous real time sensing of these solvents. At a dry cleaning facility, workplace air was analyzed using the portable GC/MS after selected ion chromatograms were produced. At a facility where volatile solvents were used to print images onto flexible vinyl, the GC/MS was used to generate real time simultaneous measurements of the ambient concentrations of the principle solvents. The author concludes that although substantial training and costs are required to run the portable GC/MS, the instrument can be highly useful for field GC/MS analysis.