The modelling of the sublimation step needs the knowledge of basic thermodynamic properties as the equilibrium solid-vapour pressures and the sublimation enthalpies. Unfortunately these thermodynamic properties are generally missing in the literature. Tert-butanol (TBA) co-solvent has been used largely as solvent in freeze-drying formulation. Thus, in the present study, we have determined the equilibrium values of vapour pressures (solid-vapour and liquid-vapour equilibrium) and sublimation enthalpies of pure TBA and for its eutectic mixture with water, namely the 90% (w/w) TBA + 10% (w/w) mixture, by using two different and comparative methods: the Thermogravimetric Method crc Method) and the Static Method. TG experiments were conducted in dynamic conditions in a temperature range from -30 degrees C to 80 degrees C. Both methods led to similar values with a relative deviation less than 2%. This validation proved that the TG method is a rapid, reliable and precise technique for the determination of solid/vapour and liquid/vapour equilibrium pressures for pure substances or for co-solvent + water mixtures at eutectic/azeotropic compositions. (C) 2011 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.