In order to make available high-purity nitromethane for thermodynamic measurements, a commercially prepared sample was purified by chemical and physical means to better than 99.9 mole per cent as determined by the freezing point method. In addition to the thermodynamic properties reported by McCullough, et al., values for freezing point, density, refractive index, viscosity and surface tension were determined on the purified nitromethane. This paper describes the purification procedures and presents values for the latter properties.