Spray drying was used to encapsulate the paraffin Rubitherm (R) NT27 with and without carbon nanofibers (CNFs) showing a microencapsulation yield of 63%. Characteristics of microcapsules containing this phase change material (PCM) were dependent on the location in which they were collected in the spray dryer. The mechanical properties of the above-mentioned materials were studied by atomic force microscopy (AFM) indicating that the force required to produce the same microcapsule deformation was approximately 183% higher when 2 wt% of CNFs was added in the microcapsule recipe. The thermal energy storage (TES) capacity of the obtained microcapsules (98.1 J/g) was similar to those exhibited by microcapsules produced by a suspension polymerization technique using styrene as shell material (96.7 J/g) and that of a commercial material (116.2 J/g). In the same way, the CNF content maintained the TES capacity of the microcapsules (95.6 J/g) and seemed to enhance their thermal conductivity. Finally, the stability studies of the synthesized material carried out during 3000 cycles indicated that the developed material was stable and worked in reversible way. (C) 2010 Elsevier B.V. All rights reserved.