A numerical method is presented to determine the temperature dependent thermal conductivity and heat capacity from the temperature measured at boundaries in a medium. The undetermined thermophysical properties are denoted as the unknown variables in a set of nonlinear equations, which are formulated from the measured temperature and the calculated temperature at the medium's boundaries. Then, an iterative process is used to solve the set of nonlinear equations. Two sensors are needed to measure the temperature in the medium. The results show that the speed of convergence is considerably fast because the number of iterations to approach a satisfied solution is under seven times. The close agreement between the exact values and the estimated results is made to confirm the validity and accuracy of the proposed method. (C) 2000 Elsevier Science Ltd. All rights reserved.