Substrate characterization experiments were carried out on different feedstocks and structure materials considered appropriate for use in dry anaerobic batch digestion systems. Physical material characteristics tested were bulk and saturated bulk density, compressed density, permeability, compactibility, water holding capacity, maximum water content, and volatile solid content. Oedometer tests were conducted on prepared feedstock/structure material mixtures targeting a high permeability under compression. Porous materials such as straw and woodchips were tested to determine if they enhance material mixture properties to yield superior permeability and allow percolation.