The mass spectra of some monomethylquinolines, dimethylquinolines, monoethylquinolines and monopropylquinolines have been determined. In addition, the spectra of 1,2,3,4-tetrahydroquinoline, 5,6,7,8-tetrahydroquinoline and some monomethyl-1,2,3,4-tetrahydroquinolines have also been studied. Fragmentation mechanisms are proposed to account for the most important peaks in the spectra of these compounds. Deuterium labelled analogues of many of the compounds have been prepared and their spectra support the proposed fragmentation mechanisms. / Thesis / Doctor of Philosophy (PhD)