In the present work studies of experimental nature were made to evaluate the importance of the wall surface configuration related to its overall thermal resistance. A parameter with major importance in the value of such resistance is the convection heat transfer coefficient. In this way, several different surfaces were built and the correspondent convection coefficient was determined for natural convection conditions. As a reference for the comparative study a smooth surface has also been constructed. The value of the convection coefficient for each surface was obtained with the help of an infrared thermography system. The obtained results show a reasonable reduction in the smooth surface convection coefficient, which leads to an increase in overall thermal resistance. Therefore, if the objective is to increase the heat transfer rate between a surface and its neighbours there should be used roughness surfaces. (C) 2005 Elsevier B.V. All rights reserved.