The materials using PCM characterized by considerably higher the effective heat capacity than the commonly used construction materials. Heat accumulations is due not only to increase their temperature (heat capacity), but it’s connected with the isothermal phase change (most melting). It characterized by a heat of transformation, so, latent heat. PCM materials played a role in the AAC blocks heat or cold battery, which would consume surplus heat from various sources and released them into the room during periods of low temperature outside. In the way it reduces the fluctuations of the room temperature, reducing it the extent compatible with the requirements of thermal comfort. In the article the authors present research possibility of the use of phase change materials PCM to the production of autoclaved aerated concrete AAC. Research the influence of the changeable amount PCM on properties autoclaved aerated concrete will also stay in this paper. Research of properties autoclaved aerated concrete will be conducted according to EN 771-4.