The sorptivity is an easily measured material property which characterizes the tendency of a porous material to absorb and transmit water by capillarity. Its theoretical basis in unsaturated flow theory is reviewed, together with methods of measurement suitable for cement-based materials. Available data on mortars and concretes are included. The dependence of the sorptivity on initial water content, temperature and fluid properties is also described. Other test methods (the initial surface absorption, the Figg water absorption and the Covercrete absorption tests) are discussed in terms of the sorptivity.