Smart gypsum composites were manufactured by adding different kinds of microcapsules containing phase change materials (PCMs) in order to develop building materials with high thermal energy storage (TES) capacity useful for being applied in high comfort constructive systems. The physical, thermal and mechanical properties of these composites such as density, porosity, thermal stability, thermal conductivity (k), equivalent heat capacity (c(p)), the accumulated heat power (q(acc)) and the maximum compressive strength were studied. Results showed that the higher the microcapsules content, the lower the density and k and the higher the c(p) and q(acc), due to the PCM action. Besides, the addition of 15 wt% of microcapsules respect to the hemihydrate would allow to save 4.5 kWh of energy per operating cycle in a standard room covered with 1 m(3) of this gypsum. This energy is equivalent to the energy spent by three incandescent light bulbs of 60-W kept on all the day and a reduction of 1.395 kg of CO2 emissions to the atmosphere. The addition of these thermoregulating materials to gypsum decreases their compressive strength but all the developed materials satisfied the Spanish mechanical regulations for gypsum as building material, being possible to increase the total amount of added microcapsules. (c) 2014 Elsevier B.V. All rights reserved.