The use of concentrated solar energy for pyrolysis and gasification of biomass is an efficient means for production of hydrogen rich synthesis gas. Utilizing molten alkali-carbonate salts as a reaction and heat transfer media offers enhanced stability and higher reaction rates to these solar processes. To establish the reaction kinetics, experiments were carried out in an electrically heated molten salt reactor. Cellulose or activated charcoal were pyrolyzed or gasified with steam from 1124 K to 1235 K with and without salt. Arrhenius rate expressions are derived from the data supported by a numerical model of heat and mass transfer. The average rate of the reactions in molten salt, as measured by their reactivity index, is increased by 70% for pyrolysis and by an order of magnitude for steam gasification.