In most cases, building materials contain, after their incorporation into a structure, a certain amount of moisture that affects their thermal insulation properties, mechanical properties and ultimately their life. In case of autoclaved aerted concrete (AAC), a large amount of moisture is introduced into the material already during its manufacture (shipping moisture of cellularconcrete products often exceeds 35%). After the erection of a building structure and starting its use, the amount of integrated moisture is often very high, which leads primarily to the degradation of thermal insulation properties. The paper deals with the study of thermal and moisture behavior of different types of AAC products for masonry structures, especially in terms of changes in thermal insulating properties of the materials depending on moisture content and also depending on temperature.