Superabsorbent polymers (SAPs) are a new and promising additive used in the building industry. They are mostly used to mitigate autogenous shrinkage. SAPs, however, have various effects on concrete properties and the most important influence is the possible change in microstructure due to internal curing. The microstructure is closely linked to the strength of the material and the microstructure is thus a key property. Dynamic water vapour sorption (DVS) may be used to characterize the change in pore structure of cementitious materials, but the technique is difficult to interpret. In the present paper, DVS measurements were performed to characterize the changes induced by SAPs in the textural and sorption properties of the material. Different models were hereby applied to study pores in the micro- (Dubinin-Radushkevich) and mesopore (Barrett-Joyner-Halenda) range and to better interpret the sorption measurements. The results show that cement pastes with SAPs and without additional water show a slight decrease in the micro- and mesopore range. The results are closely linked to a cement paste with the same effective water-to-cement ratio. Cement pastes with SAPs and with additional water show no significant difference in the micropore range and a slight increase in larger mesopore range. These new findings give insight into the effects of SAPs on the microstructure and strength of cementitious materials.