Crystallization of sugars produces signifi cant effects on the sensory and physical properties of food. Whereas crystallization of sucrose has received much attention, crystallization of polyols has not been well researched. Lactitol ([+] - 4 - O - â - D -galactopyranosyl - D - glucitol), a polyol, is being used increasingly as a sweetener in foods. This project studied the crystallization behavior of lactitol in order to better control the processing and quality of lactitol products. It was studied using two main approaches: (a) the melting enthalpy of the crystallizing lactitol samples and (b) their moisture sorption. The degree of crystallinity of lactitol during storage was determined by the melting enthalpy during storage. An iterative modeling equation was developed to describe the crystallization behavior of lactitol based on its moisture - sorption pattern. This model was based on the moisture adsorption of the amorphous lactitol, the moisture desorption of the crystalline lactitol, and the crystallizing lactitol, which was modeled using the Avrami equation. The rate of crystallization increased with increased temperature and relative humidity (RH). Lactitol crystallized down to 30% RH at 20 ° C and down to 22% RH at 32 ° C. The glass transition temperature of lactitol was successfully used to predict whether crystallization would occur at different storage temperatures and relative humidities.