The method of capillary rise in a random bed of particles, as measured by the rate of mass increase of packed beds of sample particles, was applied to measurements of the relative wetting characteristics of selected particulate carbonaceous fuels by different molten electrolytes of general interest in electrochemical energy applications. In particular, a series of activated chars as well as Pittsburgh (#8) and Beulah-Zap lignite coal samples (both as-received and pyrolyzed) were investigated. It was found that the wetting coefficient (k = cos theta) of the molten electrolytes (NaOH, KOH, a binary NaOH/KOH eutectic mixture, and a ternary alkali metal carbonate eutectic) on an activated char all increased with the temperature in an approximately linear fashion over the limited temperature ranges investigated. It was also found that the wetting coefficient increased with decreasing particle size. This was observed for both the activated chars and the coal samples. In addition, it was found that pyrolysis significantly improved the wetting of both coals investigated. In the current work, this was attributed to increasing the concentration of mineral matter in the resultant pyrolyzed samples at the liquid-solid interface.