The density gradients present in several aluminium foams, produced by the powder metallurgical route, have been analysed by using computed tomography and by measuring the effective thermal conductivity (lambda). The method used to measure lambda, Transient Plane Source (TPS) technique, allows obtaining values of the local thermal conductivity, i.e. conductivity of a localised zone within the sample. These values have been related to the density of the measured zone, which was obtained from the computed tomography experiments. A power law relationship between local effective thermal conductivity and local density has been obtained.