Hydrated cobalt(II) and nickel(II) trifluoromethanesulfonates have been prepared by a previously reported procedure, and have been characterized for the first time as [Co(H2O)6] (CF3SO3)2H2O and [Ni(H2O)6] (CF3SO3)2. These formulations are based on analyses, near-infrared spectra, and on measurements of the ligand field electronic spectra and the magnetic susceptibilities. The metal ions are high-spin and octahedrally coordinated in both compounds. Methods have been developed for the preparation of the pure anhydrous cobalt(II) and the previously unknown nickel(II) trifluoromethanesulfonates from the hydrates. By determination of the d-d spectra and the magnetic moments, these are found to contain high-spin octahedrally coordinated metal cations, and therefore contain coordinated trifluoromethanesulfonate anions. The near-infrared spectral absorptions of these anions have been observed. The magnetic moment reported by previous workers for anhydrous cobalt(II) trifluoromethanesulfonate corresponds to the value found in this work for the hydrate. By vacuum line methods, pressure-composition data have been obtained for the triethylamine-cobalt(II) and nickel(II) trifluoromethanesulfonate systems. Breaks in the 25° isothermal phase diagrams show that very unstable adducts containing two molecules of triethylamine per metal ion are formed in each system. These could not be isolated. Various experimental methods for the preparation of quinuclidine complexes were investigated. The one found to be successful involved mixing, by Schlenk techniques, acetonitrile solutions of the anhydrous metal trifluoromethanesulfonate and of an excess of quinuclidine, evaporating the solvent, and removing the excess quinuclidine by sublimation. The solid complexes obtained in this way were characterized as [Co(QUIN)4] (CF3SO3)2 and [Ni(QUIN)2(CF3SO3)2] by their analyses, ligand field spectra, magnetic moments, and the near-infrared absorptions of the anions. As expected, quinuclidine is found to be a better ligand than its more sterically demanding analogue, triethylamine. The quinuclidine complexes of cobalt(II) and nickel(II) trifluoromethanesulfonates are much more stable. In the case of the cobalt complexes, the metal ion has a greater ligation number for quinuclidine than for triethylamine. In these solid salts and complexes, the trifluoromethanesulfonate ion shows a much greater tendency to coordinate than had been expected, based on a previous study using it in aqueous solution.