A reactive distillation process is disclosed for the selective oxygenation of a biomass. The biomass may be a ligno-cellulosic biomass, or a bio-oil. The process comprises the steps of contacting a biomass slurry with a particulate inorganic material, and heating the mixture to its boiling point. In a preferred embodiment water vapors emanated from the process are collected and condensed to provide a source of fresh water.