A study of the reduction of nitroglycerin with titanous sulphate has been carried out. The results indicate that for each mole of nitroglycerin reduced, 18 moles of titanous ion are oxidized, two moles of ammonia, one-half mole of nitrogen trioxide, and one mole of glycerol are formed. It has been shown that the reduction takes place first to 1,3-dinitro-2-nitrosoglycerin which, after hydrolysis to 1, 3-dinitroglycerin, is reduced to glycerol with the probable intermediate formation of 1, 3-dinitrosoglycerin. The determination of nitroglycerin by the Shankster and Wilde method is more accurate when 70% acetic acid is substituted for methanol as the solvent for nitroglycerin.