In general, PCM are classified in organic and inorganic groups or families. First group mainly encloses paraffin, fatty acids, and sugar alcohols. Inorganic are mostly represented by salt hydrates, salt solutions, and metals. Eutectics and mixtures are also being formulated to obtain a desired phase change temperature. One of the most important PCM requirements is being stable after a number of repeated melting/freezing cycles, which is known as cycling stability. A PCM should present the same or almost the same thermal, chemical and physical properties after a repeated number of freezing and melting cycles. Thermal cycling tests results and detailed tests procedures are classified by PCM type in this review. Moreover, the parameters that must be considered in order to perform cycling stability tests are highlighted depending on the importance they have on the following four issues: the choice of the equipment to perform the cycling tests; the selection of the techniques to characterize the PCM before and after thermal cycling test and to follow the PCM thermal degradation; the definition of the number of cycles to perform; and finally, the choice of the heating rate and thermal cycling method (pyramid, or dynamic, or others) to perform the tests. It is mandatory to conclude that, based on the literature reviewed, no common standard for thermal cycling stability tests is available at the moment.The research leading to these results has received funding from the European Commission Seventh Framework Programme (FP/ 2007-2013) under grant agreement No. PIRSES-GA-2013-610692 (INNOSTORAGE). Furthermore, the work is partially funded by the Spanish government (ENE2011-28269-C03-02 and ENE2011- 22722). The authors would like to thank the Catalan Government for the quality accreditation given to their research groups GREA (2014 SGR 123) and DIOPMA (2014 SGR 1543). Aran Solé would like to thank the Departament d'Universitats, Recerca i Societat de la Informació de la Generalitat de Catalunya for her research fellowship

In recent years, thermal energy storage (TES) systems using phase change materials (PCM) have been widely studied and developed to be applied as solar energy storage units for residential heating and cooling. These systems performance is based on the latent heat due to PCM phase change, a high energy density that can be stored or released depending on the needs. PCM are normally encapsulated in containers, hence the compatibility of the container material with the PCM has to be considered in order to design a resistant container. Therefore, the main aim of this paper is to study the corrosion effects when putting in contact five selected metals (aluminium, copper, carbon steel, stainless steel 304 and stainless steel 316) with four different PCM (one inorganic mixture, one ester and two fatty acid eutectics) to be used in comfort building applications. Results showed corrosion on aluminium specimens. Hence caution must be taken when selecting it as an inorganic salt container. Despite copper has a corrosion rate range of 6e10 mg/cm2 yr in the two fatty acid formulations tested, it could be used as container. Stainless steel 316 and stainless steel 304 showed great corrosion resistance (0e1 mg/cm2 yr) and its use would totally be recommended with any of the studied PCM.The work is partially funded by the Spanish Government (ENE2011-28269-C03-02 and ENE2011-22722). The authors would like to thank the Catalan Government for the quality accreditation given to their research groups GREA (2014 SGR 123) and research group DIOPMA (2014 SGR 1543). Aran Sole would like to thank the Departament d'Universitats, Recerca i Societat de la Informacio de la Generalitat de Catalunya for her research fellowship. The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007- 2013) under grant agreement n PIRSES-GA-2013-610692 (INNOSTORAGE