Several different diesel particulate filter (DPF) structures have been characterized for filtration performance. The physical structures of the DPF ceramic materials considered are dramatically different (i.e. deep foam bed, thin fibrous nonwoven. thin porous extrusion). Due to these differences in structure and the way these DPFs are applied. different filtration mechanisms dominate the collection of diesel exhaust particulates. Laboratory measurements of ceramic DPFs were made including: particle collection efficiency versus particle size and total pressure loss at several velocities. Good correlations between modeled behavior and laboratory experiments have been achieved, indicating that the OPF structures have been accurately characterized. A detailed understanding of a DPF structure leads to an improved knowledge of its filtration behavior and a better DPF system design.