SiOC microcellular ceramic foams were prepared by means of a commercially available preceramic polymer and poly(methyl methacrylate) microbeads acting as a sacrificial filler. Microfoams having cell sizes in the range of 10-150 mu m and cell window sizes in the range 10-50 mu m were prepared. To test the applicability of such materials in the fluid flow field, gas permeability measurements were performed. The relationship between the permeability constant and morphological parameter were analyzed. An aerosol filtration process was simulated on the samples and revealed the feasibility of this process only for larger cell size foams.