X-ray tomography is used to produce three-dimensional images of an aluminium alloy foam with a high porosity (>93%). These data allow describing the foam structure from which a finite element model is derived to predict the thermal conductivity of the foam. The results are compared with experimental values measured by a new guarded hot plate apparatus adapted for the range of thermal conductivity values of interest. Good agreement is observed which validated the finite element model used to evaluate the thermal properties of any porous metallic foam with stochastic cell size and configuration. Furthermore, the thermal conductivity of the foam has also been predicted using previous analytical models. The differences with previous values show that it is important to account for the real geometry of the foam to get an accurate value of the thermal conductivity.