Oxy-fuel combustion, particularly using an integrated oxygen ion transport membrane (ITM), is a thermodynamically attractive concept that seeks to mitigate the penalties associated with CO2 capture from power plants. Oxygen separation in an ITM system consists of many distinct physical processes, ranging from complex electrochemical and thenno-chemical reactions, to conventional heat and mass transfer. The dependence of ITM performance on power cycle operating conditions and system integration schemes must be captured in order to conduct meaningful process flow and optimization studies where multiple degrees of freedom are considered. An axially spatially-distributed, quasi two-dimensional model is developed based on fundamental conservation equations, semi-empirical oxygen transport equations obtained from the literature, and simplified fuel oxidation kinetic mechanisms. Aspects of reactor engineering such as geometric structure, flow configuration and the relationship between oxygen transport, fuel conversion and pressure drop are explored. Emphasis is placed on model robustness, modularity, and low computational expense in order to evaluate the myriad of ITM possibilities within a power cycle simulation quickly and accurately. Overall, the model seeks to bridge the gap between detailed CFD studies and overly-simplified black-box models found in ITM-power cycle analyses, and provides a tool for the analysis and design of ITM systems. (C) 2011 Elsevier Ltd. All rights reserved.