Abstract Thermal diffusivity and specific heat at constant pressure of a collection of crosslinked closed cell polyethylene foams have been measured at room temperature using the transient plane source (TPS) method. A theoretical model to predict the thermal diffusivity has been proposed. The predictions of this model are in good agreement with the observed experimental trends. The theoretical model predicts a dependence of the thermal diffusivity on the density and other foam characteristics such as carbon black content and cell size. Copyright © 2004 Society of Chemical Industry