Water absorption and desorption of the diglycidyl ether of bisphenol A (DGEBA)/4,4’-diaminodiphenyl sulfone (DDS) resin systems, cured isothermally at three different temperatures (160, 180 and 220-degrees-C), were monitored at 80-degrees-C, as a function of soaking and drying times. New near infra-red spectroscpoic (NIR) technique as well as the conventional gravimetric method were used. The data from two different techniques were reasonably identical showing that the new NIR technique is valid. The resin systems cured at higher temperature absorbed more water. The degree of structural packing of the network systems has been estimated from the observations in water absorption characteristics.