Micropyretic/combustion synthesis is a technique whereby a material is synthesized by the propagation of a combustion front across a powder. Heterogeneities in initial composition and porosity are commonly occur-red during micropyretic synthesis when powders are pressed or mixed and the conventional modeling treatments thus far have only considered uniform systems. Heterogeneities in the initial composition and porosity are thought to result in local variations in reaction yield and such thermophysical/chemical parameters for the reactants as density, heat capacity, and thermal conductivity; further changing the average propagation velocity and the oscillatory pattern of an unstable combustion front. This study thus investigates the impact of heterogeneities in composition and porosity on the unstable micropyretic synthesis with Ti+2B by a numerical simulation. The heterogeneity maps, considering the composition and porosity heterogeneities concurrently, are also generated. The maps provide a better understanding of the heterogeneous composition and porosity effect on the average propagation velocity and oscillatory frequency during unstable micropyretic synthesis. (C) 2004 Elsevier Ltd. All rights reserved.