Abstract This study is the first of a three-part research program which involves fuel characterization, testing in a 1 MWth gasifier, and computational fluid dynamics (CFD) modeling for entrained-flow slagging gasification. Focus is on the behaviour of inorganic fuel components since the end goal is to develop a CFD model which includes inorganic matter transformations. Initially, four coals were selected for this program and one limestone was also chosen to act as a fluxing agent. Fuel properties related to ash particle formation, gas-particle transport, particle sticking, slag flow and slag-refractory interaction are provided with prioritization based on their potential application for screening of potential fuels, ensuring proper gasifier operation, gasifier design and/or CFD modeling. The selection of one or multiple experimental and/or modeling techniques is justified and applied to determine each relevant property. Of the four coals tested, one was deemed unsuitable based on initial screening tests. Two of the three remaining coals require fluxing for proper gasifier operation. Design tests showed that alumina is preferred over silicon carbide and alumina–chromia (with 30wt.% chromia) for use as refractory material with the selected fuels. Characterization for CFD modeling is also discussed with results provided as supplementary data.