The objective of our research was to measure accurate rate constants for the thermal, unimolecular decomposition of organic nitrates. Our research confirms that the rate-determining step is homolytic cleavage of the weak O-N bond to form alkoxy radical and NO2, but the rate constants reported in the past are incorrect. The alkoxy radical and NO2 engage in secondary reactions that ultimately generate stable products such as carbonyl and nitro compounds. Infrared spectroscopy (IR) and gas chromatography/mass spectrometry (GC/MS) were used to monitor the time dependent loss of organic nitrate and to characterize the products of the thermal reaction. Past research indicates that oxygen slows the rate of homolytic O-N bond cleavage to form radicals. Our research shows that the rates are the same in nitrogen as they are in air. The reaction in air produces alpha-beta unsaturated ketones/aldehydes, which are not generated in a nitrogen atmosphere. The unsaturated ketone/aldehydes complicate the IR analysis, giving the appearance that the loss of organic nitrate slows down. Unhindered, linear organic nitrates have lower reaction rate constants than hindered organic nitrates. Activation energies were found to be lower for hindered organic nitrates. The steric strain present in the hindered organic nitrates may account for the weaker O-N bonds and faster thermal reaction rates. Reaction rates for thermal decomposition under nitrogen were found to decrease as the viscosity of the solvent increased.