The objective of this proposed research is to develop a low cost, high performance filtration media that exceeds the performance of that which is presently available for the construction of HEPA filters. The basis for the media is a low density microcellular foam process that was developed originally at Sandia National Laboratories. This foam process will be combined with electret formation process to create a microcellular electret foam filtration media. The experimental program is directed towards gaining insight into the interaction between the necessary fabrication processes and the solvent/polymer solution required to create the foam and resolution of identified problems in the adaptation of the foam to filtration applications. Also, the incorporation of electret formation equipment into the fabrication process will be investigated. The knowledge gained will be used to develop a set of guidelines for the design and production of a microcellular foam filtration media.