The steam reforming of acetol and hydroxyacetaldehyde, intermediate compounds formed during biomass pyrolysis and gasification, has been investigated over natural calcite and olivine materials in the temperature range of 550-650 degrees C. Calcite was employed in three different forms: as received, calcined/recarbonated and calcined (as CaO). All catalytic tests were carried out in a quartz reactor, since high reactivity of the two compounds was observed when the reactor was made of stainless steel. Calcined calcite in the form of CaO was the most active catalyst in the transformation of both organic molecules under steam reforming conditions. This correlates to its higher specific surface area compared to the other catalysts. A multitude of organic products as well as CO, CO2 and H-2 were observed in the course of the reaction resulting from a stepwise decomposition pathway of the two oxygenated molecules and the occurrence of the water-gas shift reaction.