This unique book demonstrates the current status, and future potential, of millimetre wavelength (MMW) spectrometry as a means of quantitative analysis of gaseous mixtures. After outlining the spectroscopic theory required, the authors then go on to discuss the components of an MMW cavity spectrometer, concentrating on compact, automatic, low-cost instruments. Other topics covered include solid state MMW sources with both cryogenically cooled and room temperature detectors, Post-detector signal processing, smoothing, filtering and spectral profile fitting are also discussed. The book concludes with a look at the future of the technique, in areas such as millimetre wave-over-fibre technology. Quantitative Millimetre Wavelength Spectroscopy will be welcomed by practitioners in both industry and academia.