The time dependence of water vapour absorption by superabsorbent polymer clay composite (SAPC) hydrogels was studied using thermophysical methods. For the purpose of comparison the average value of the specific interaction enthalpy of liquid water with the SAPC structure was calorimetrically determined for a defined interaction time. Dynamic vapour absorption measurements confirmed that the SAPC material has a sufficiently high absorption capacity and good selectivity for water vapour. A prototype moisture sensor with excellent reproducibility of the output voltage signal was constructed by coating a silicon integrated thermotransducer with a thin SAPC membrane.