The thermal behavior of vibro-compressed concrete hollow blocks with one or more incorporated layers of thermal insulating material has been analyzed. The analysis of thermal resistance has been performed with the finite elements method, according to the EN 1745. The walls, built with the analyzed blocks, are able to widely satisfy the limit values of thermal transmittance imposed by the national legislation. The thermal transient behavior of the examined walls has been studied with reference to the following parameters: decrement factor, time lag and dynamic thermal transmittance. The thermal transient performance of the walls, made with the proposed blocks (made of both heavy and light concrete), have been studied for a period varying in the range 10÷200 hours to take into account the outdoor temperature oscillation in a day and in a longer period as one week.