A study was conducted on a new granular material (Lapilli) for hot gas filtration. We have characterized this material by means of set of instrumental methods involving: surface area (S-BET), scanning electron microscopy (SEM), X-ray diffractometry (XRD), thermogravimetry (TG), differential thermal analysis (DTA) and X-ray fluorescence (XRF). Also, we have used a fixed bed heat exchanger-filter (FHEF) for removing fine dust particles from gases. The influence of a number of variables was examined, including gas velocities, filter height and gas temperatures and the collection efficiency was found to decrease with increasing temperature. Also, a model was proposed to describe the granular filtration of the FHEF using Lapilli as a granular medium. A numerical solution of the filtration equations based on the finite element method was presented. (c) 2006 Elsevier B.V All rights reserved.