An inverse conduction-radiation problem for simultaneous estimation of the single scattering albedo, the optical thickness, the conduction-to-radiation parameter, and the scattering phase function from knowledge of the exit radiation intensities is presented The inverse problem is solved by using the conjugate gradient method to minimize the error between the calculated exit intensities and the experimental data. The effects of the measurement errors, the conduction to-radiation parameter, the single scattering albedo, the scattering phase function, and the optical thickness on the accuracy of the inverse analysis are investigated. The results show that the single scattering albedo and the optical thickness can be estimated accurately for exact and noisy data. Estimation of the conduction-to-radiation parameter and the scattering phase function is more difficult than that of the single scattering albedo and the optical thickness because the prediction of the former properties is more sensitive to the measurement errors. 1998 Elsevier Science Ltd. All rights reserved.