The moisture sorption isotherms of Greek durum wheat semolina were determined at 25, 30, 35, and 40°C using the gravimetric (static) and the Novasina hygrometric methods. Good agreement was found between sorption isotherms for semolina obtained with the Novasina and the static gravimetric methods. Sorption isotherms were of the characteristic sigmoid shape (BET type II). Sorption data showed that the moisture content increased while water activity was increasing at a constant temperature, and decreased while temperature was increasing at a constant relative humidity. The water vapor sorption kinetics of semolina was also studied using the static gravimetric method. With the temperature and relative humidity rising, the rate of water sorption also increased. The increase, though, was not stable. Initially, there was a steep rise, but while moisture contents reached equilibrium the rate was substantially decreased. The experimental data were successfully fitted to 7 of widely used isotherm models (B.E.T., G.A.B., Freundlich, Halsey, Henderson, Chung and Pfost, and Oswin). Isosteric heat of sorption (ΔHs) of the studied substrate (semolina) was also determined using the modified Clausius–Clapeyron equation. The steep increase (absolute values) of ΔHs at low moisture contents indicate that water molecules interact more strongly at lower moisture contents.