A model for predicting the degradation mode of high-temperature coating is developed in this paper based on Fick's law. The degradation formula is deduced according to this model and then used for predicting the working lifetime of the coating on the basis of the dependent relation among the effective thickness of the coating, the oxidation time and the thickness of the degradation layer resulting from oxidation and coating-substrate interdiffusion. Finally combination of the dominant degradation mode and formula gives the possible measures taken to improve the oxidation-resistant property of the coating. (c) 2006 Elsevier B.V. All rights reserved.