The temperature influence on measurement of sorption isotherms of porous building materials, namely sandstone and ceramic brick, is described in the paper. The measured results show that temperature highly effected moisture content adsorption on porous surface. On this account it is very important to ensure constant temperature during adsorption isotherm measurement. The main aim of this experimental work is to obtain sufficiently accurate input data for the computational modeling of coupled water and salt transport and storage which is used to for the damage assessment of building structures.