Rigid polyurethane (RPU) foams were synthesized incorporating up to 18 wt % of two different kinds of thermo-regulating microcapsules having a different shell material consisting of polystyrene or poly(methyl methacrylate), named as mSP-(PS-RT27) and Micronal (R) DS 5001X, respectively. The type of microcapsules and their content affected the final foam height, which decreased with the content and particle size. However, the foam rising curve shape was not dependent on the microcapsules type or content and was successfully predicted by means of a model of reaction curve of four tanks in series. Thermal energy storage (TES) capacity of PU foams was improved by incorporating both, mSP-(PS-RT27) or Micronal (R) DS 5001X, with the values close to those reported in the literature (16 J/g) for the highest content. Nevertheless, the highest particle size of the microcapsules from PS and the agglomeration of the microcapsules from poly(methyl methacrylate), promoted by their additive SiO2, led to the strut rupture, damaging the final mechanical properties. (C) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 128: 582-590, 2013