Particulate filtration systems are currently being developed for use in advanced coal-fired process applications. In these applications rigid ceramic barrier or fabric bag filters operate at high temperature and pressure in either combustion or gasification environments which contain variably sized ash, char or sorbent fines. The potential exists for gas phase alkali, as well as volatile chloride and sulfur species to also be present in the particulate-laden effluent gas streams. This paper provides a review of the morphology and composition of the ash, char and sorbent fines which deposit in the dust cake layers along ceramic barrier filters in advanced coal-fired combustion and gasification subpilot and demonstration plant test facilities. The presence of condensed alkali, chloride and sulfur species in the ash cake deposit is also explored.