In recent years, storage of thermal energy has become a very important topic in many engineering applications and has been the subject of a great deal of research activity. This paper reviews the thermal energy storage technologies suitable for building applications with a particular interest in heat storage materials. The paper provides an insight into recent developments on materials, their classification, their limitations and possible improvements for their use in buildings. Three major thermal energy storage modes (sensible heat, latent heat, thermochemical heat) are described emphasizing the main characteristics of the most suitable heat storage materials for each.