The sublimation kinetics of amino acid L-leucine is studied with the isothermal thermogravimetric (TG) analysis at temperatures between 400.7 and 517.5 K. Sublimation Of L-leucine follows zero order kinetics. L-leucine begins to Sublime around 423.2 K and Sublimation rate increases exponentially with increasing temperature. The vapour pressure Of L-leucine is determined based on the mass loss rate showing a good cot-relation with literature values. Using the Arrhenius equation, the activation energy and pre-exponential factor are determined. The sublimation enthalpy and entropy are obtained using the Clausius-Clapeyron equation. (C) 2008 Elsevier B.V. All rights reserved.