Contemporary ceramic blocks with the cavities filled by thermal insulation materials appeared in some European countries as a reaction of the brick industry to the increasing requirements on the energy efficiency of buildings. Their dual load-bearing and thermal insulating function, together with the good building-physical qualities and technological advantages makes them competitive on the building materials market. The assessment of their thermal properties is, however, a demanding task which often involves using large-scale experimental facilities for considerable time periods. In this paper, an alternative to the commonly used methods for determination of thermal performance of ceramic blocks with complex internal geometry is presented. The proposed approach is based on the computational modeling of heat transfer in the block, using the thermal properties of involved materials measured in a laboratory experiment as input parameters. The calculated temperature fields and heat fluxes are used for the determination of the effective thermal conductivity, thermal resistance and thermal transmittance. A practical applicability of the method is demonstrated for three ceramic blocks with different thermal insulation materials in the cavities. An uncertainty analysis of the calculated thermal parameters is performed and the results are compared with the data obtained by two different experimental approaches. (C) 2015 Elsevier B.V. All rights reserved.