Recently, several studies have been published on the spray drying of sucrose and other low-molecular-weight sugars which are typically sticky materials. Sticky materials can not be processed under normal drying conditions and may require addition of high-molecular-weight carbohydrates such as maltodextrin. Predicting appropriate drying conditions are however difficult due to the unavailability of drying kinetics. In this article, we have formulated the drying kinetics model using the reaction engineering approach (REA) for the drying of aqueous sucrose and aqueous maltodextrin (DE6) droplets. The relative activation energy was empirically obtained based on experimental measurements. To model the drying of droplets containing both solutes (sucrose and maltodextrin), a new "composite" REA has been established and presented here for the first time. Results demonstrated that the composite REA forms a reliable framework to model the drying of aqueous solutions of pure carbohydrates and their mixtures. (C) 2008 American Institute of Chemical Engineers AIChE J, 55: 217-231, 2009