Thorium is shown to react with 3-methyl-8-hydroxyquinoline in the molar ratio 1:5, but isolation of the pure anhydrous compound requires special precautions. Thermogravimetry and differential thermal analysis of the compound indicate, amongst other things, the existence of a thorium 3-methyl-8-hydroxyquinolate of 1:4 stoichiometry. The pH dependence of the precipitation of thorium 3-methyl-8-hydroxyquinolate is determined, and correlated theoretically, with data for thorium 2-methyl-8-hydroxyquinolate. Thermal and other studies on thorium 8-hydroxyquinolate emphasize its anticipated similarity to the 3-methyl-8-hydroxyquinolate, and its differences from the 2-methyl compound. The precipitation of at least two compounds of thorium and 8-hydroxyquinoline is demonstrated. 3-Methyl-8-hydroxyquinoline is established as a sensitive reagent for determining thorium by both bromometric and polarographic methods with good precision and accuracy. / Thesis / Master of Science (MS)