A review of multiphase catalytic processes in biomass conversion is presented, with an emphasis on the underlying kinetics, mechanism, and reaction engineering aspects. The distinguishing features and current state of development of catalysts and processes for a few selected examples of biomass conversion are presented, including hydrogenolysis and tandem reforming/hydrogenolysis of polyols to glycols and linear alcohols, hydrodeoxygenation of bio-oils, and polyols conversion to lactic acid along with possible reaction pathways. The complexities of multistep and multiphase catalytic reactions and kinetics modeling associated with hydrogenolysis and hydrodeoxygenation are discussed with a brief overview of reaction engineering aspects.