Monolithic honeycomb reactors are characterized by small parallel channels, which make them an interesting approach to be applied as microstructured reactors. Besides the established manufacturing of ceramic honeycombs, these structures exhibit excellent mass transfer characteristics for multiphase reactions combined with degrees of freedom in the structural design. The potential of monolithic honeycomb reactors operated in the beneficial slug flow regime is evaluated for heterogeneously catalyzed gas-liquid reactions. Results of the Fischer-Tropsch synthesis and hydrogenation of glucose to sorbitol were analyzed in order to obtain a more generalized picture of the interaction between mass transfer and reaction in small channels operated in multiphase flow.