The present study investigates a monolithic silica microhoneycomb including ammonium molybdophosphate (AMP-SMH) that was synthesized for cesium separation in a continuous flow system. The honeycomb structure of the AMP-SMH causes significantly less hydraulic resistance to a liquid flow than a conventional bed of particles as demonstrated by pressure-drop measurements using water. AMP particles were dispersed as small particles approximate to 10 mu m in diameter on or within the microchannels of the silica microhoneycomb as characterized by SEM. These AMP particles function as effective sorbents to remove ppm-level cesium ions effectively from a solution, as shown by the breakthrough curve. These data suggest the potential features of the AMP-SMH for processing a large volume of a solution containing radioactive cesium.