Radial temperature profiles of plutonium dioxide powder in a cylindrical vessel were measured over a pressure range of 0.055 to 334.4 kPa with two different fill gases, helium and argon. The powder provides a very uniform self-heating medium for analysis. A thermal conductivity model was developed for heat conduction in the fine ceramic powder. Most literature models make limiting assumptions about powder characteristics that do not hold for this material. Despite the powder particles' complex geometry, the proposed model correctly reproduces the powder temperature profiles over the wide pressure range for both fill gases. (c) 2006 Elsevier Ltd. All rights reserved.