The Department of Energy is sponsoring a multiphase program to investigate the filtration potential of the moving granular bed filter (GBF) for application in pressurized high temperature energy conversion systems. The completed Phase I, included the development of a mathematical model, a cold flow parametric test series in a 0.746 m/sub 0//sup 3//s GBF, and investigations of potential dust plugging problems at the inlet screen. During the experimental program, collecting efficiencies of 99% and filter outlet loadings less than 0.0074 g/m/sub 0//sup 3/ were demonstrated. The objectives of Phase II are to investigate the effects of elevated temperature and coal combustion particulate on GBF filtration performance; to update the analytical model developed in Phase I to reflect high temperature effects; to optimize filter internal configuration; to demonstrate long duration GBF performance relative to corrosion, deposition, erosion, filtration efficiency, reliability and controllability. Hot flow testing to date has confirmed that the GBF configured with inlet and outlet screens has exhibited a tendency for extensive and irreversible ash plugging. As an alternative, the potential advantages produced by a screenless configuration, having higher filtration efficiency, have been achieved during both cold flow and hot flow tests as previously reported. The continuation of experimental work pertinent to the development and design improvement of the GBF system is described and specifically addresses: an experimental study of granular flow coupled with countercurrent gas flow to define the flow and velocity profiles of moving filter media; and ambient parametric testing of the screenless granular bed filter in the full scale cold flow model to determine bounds for its operation and to provide a data base from which comparisons can be made with a mathematical model describing GBF performance.