A mathematical model for the galvanostatic discharge of a porous manganese oxide particle, similar to those found within primary alkaline battery cathodes, is presented. Asymptotic techniques are employed to obtain the leading order spatial and temporal behavior of the particle. It is found that there is an initial rapid transient adjustment within the crystals forming the particle followed by a prolonged relatively uniform discharge regime which leads finally to a faster, particle-based, nonuniform discharge behavior. Analytical solutions of the model are obtained which describe the majority of the particle behaviors under a wide range of industrially relevant discharge conditions. These solutions are supplemented by simple numerical solutions where required. A comparison of the results with those obtained by a previous, more complete and accurate model is presented. The analysis shows that the particle radius, the applied discharge current, and the solid phase conductivity are the critical parameters that dictate the utilization of active material across a wide range of discharge conditions. The effect of these parameters on particle utilization is also presented. (c) 2005 The Electrochemical Society.