Biomass contains inorganic elements, such as Na, K, Ca, Mg, Si, S, and P, which vary in concentration depending upon the source of biomass and can influence the chemistry in biomass-processing techniques. The effect of these inorganic constituents in biomass on Rh catalysts for catalytic gasification by ethanol autothermal reforming has been studied. The same concentration of each inorganic element (0.05% atoms of inorganic/mol of ethanol) was added through a precursor to ethanol, a model compound for biomass reforming, in which the precursors were soluble. Reactor performance during doping and regeneration was used to analyze effects of inorganics on the Rh catalyst and to test the ability for regeneration. Of these elements, K-, P-, and Mg-doped ethanol operated autothermally over the 6 h test period, whereas Si, S, Na, and Ca quenched the reaction. The ability of the catalyst to be regenerated after doping was investigated by switching to inorganic-free fuel. Regeneration was possible for each of the inorganics studied. Silicon shut down autothermal operation the fastest, but complete regeneration of the catalyst was achieved by passing pure ethanol. Sulfur caused extensive coke formation and disintegration of the alpha-Al2O3 support. Phosphorus increased ethanol dehydration to ethylene, indicating acid chemistry, which was observable even upon regeneration. Sodium and potassium increased acetaldehyde selectivities because of their basic nature. Calcium and magnesium accumulated at the front face of the catalyst, forming CaCO3 and MgO, respectively. No liquid slag formation was observed with any of the inorganics.