Date ( Pheonix dactylifera L . ) is one of the most important horticultural crops and foreign exchange earning sources of Iran. Annual products of date in Iran, has been nearly 50 million tons since 50 years ago, while 30% of this amount as losses is consumed for animal feeding. Date powder as one of the by-products is achieved by drying and milling dates waste and is used in making pastry, ice cream etc. One of the problems encountered by fruits’ powder producing industry is stickiness during drying, processing and storage. The stickiness of fruits’ powder is generally caused by the low molecular weight of sugars including fructose, glucose, sucrose as well as some organic acids in fruits. Date fruit contains these sugars as well. To control the stickiness in food processing, the amount of water content in foods and physical state of solid contents must be realized. Moisture sorption isotherms are important to determine changes in moisture content during storage of food materials, thermodynamic conditions of mixing products and decisions regarding the use of undesirable chemical and enzymes reactions. On the other hand, determination of the glass transition temperature (T g ) is the matter of importance as a powerful tool for understanding water properties in the food and control of products’ shelf life. The parameters of the final product in the drying process such as water activity, porosity, physicochemical structure and color are dependent on drying methods. The objectives of the present study were to determine and modeling moisture sorption isotherms of the dried date powder obtained by various drying methods, study of moisture sorption kinetics of date powder and effect of drying method on qualitative characteristics of dried date and its powder as well as performing thermal analysis on date powder of waste Istamaran date variety. The drying methods used in this study were: hot air, microwave and vacuum drying. Moisture sorption isotherms were determined at seven levels of water activity and three temperatures of 25, 35 and 45 °C. The appropriate model among nine well known models was selected based on the highest correlation coefficient and the smallest root mean square error and the minimum mean relative deviation modulus. The qualitative parameters included water absorption capacity (WAC), dry matter holding capacity (DHC), rehydration ability (RA) and shrinkage for dried date as well as color indices (L, a and b) for dried date and its powder. The glass transition temperature of date powder samples was measured by differential scanning calorimetry (DSC) method. Thermal analysis was performed at -90 to 100 °C at 10 °C min -1 . Six semi-empirical and theoretical models were used to model the glass transition temperature of the date powder. According to the results, the GAB model was found to be the most accurate model for predicting the equilibrium moisture content (EMC) of date powder for all treatments. The effect of drying method on WAC, DHC and RA was significant, but its effect on the shrinkage of dried date was not significant. Also, its effect on color indices was significant. Microwave dried samples had a darker color most likely due to caramelization during drying. Thermal analysis revealed that by increasing the water content from 0.013 to 0.178, T g decreased from 21.75 to -49.15 °C. T g value of the samples was predicted using various model-systems and Gordon-Taylor and Coachman-Karasz models based on the components of the considered model-systems. The results showed that none of the model-systems had a good prediction for the glass transition temperature of date powder. The results indicate that the date powder can be considered as water-glucose model-system. Also, results of water-fructose-glucose with a ratio of one to three for glucose and fructose, respectively, indicated that glucose had more effect on the glass transition temperature of date powder, therefore, samples T g may be predicted using this model. Also, the results of T g modeling for different model-systems showed that Brostow et al. model based on water-fructose-glucose with an even ratio of glucose and fructose had the best prediction of changes in date powder T g with equilibrium moisture content. The modeling of T g as a function of water activity showed that Khalloufi et al. model had a poor fitness to the experimental data, but the Roos equation indicated an acceptable fitting. The T g was not significantly affected by drying method. The values of specific heat capacity (C p ) measured for date powder samples at different levels of water activity showed that by an increase in value of temperature and water activity, the C p also increased.