The aim of this study was to evaluate the effect of moisture on the glass transition temperature (T-g), flow properties, color, and morphology of spray-dried powdered egg. Powdered egg was stored under environments with different relative humidities at 25 degrees C and the moisture sorption isotherm was determined. The Guggenhiem-Anderson-de Boer (GAB) model fitted the isotherm data well. A differential scanning calorimeter was used to determine the T-g of samples with different water activities. The T-g data were satisfactorily correlated by the Gordon-Taylor model. The results showed that the glass transition temperature of powdered egg decreased with increasing water activity. The changes in flowability based on the Carr index (CI) and cohesiveness based on the Hausner ratio (HR) with water activity were defined. At low water activity values, the powder had poor flowability and high cohesiveness. These flow properties were also supported with scanning electron microscope (SEM) images.