Flow-through microreactors are described, constructed of fused silica capillaries with an internal diameter of 100 μm and glass microchips with a channel dimension of 150 μm and involving the in situ UV-initiated synthesis of a poly(glycidyl methacrylate-co-ethylene dimethacrylate) porous polymer monolith. The monolith is a continuous material covalently bonded to the capillary or chip walls, with good flow-through properties. Epoxide ring-opening through amine attack by 5-amino-1,10-phenanthroline and coordination to dichloropalladium(ii) allows use of the microreactors for Suzuki–Miyaura catalysis. The long-term stability and reliability of the robust chip microreactor is demonstrated by operation for 96 h, exhibiting undiminished reactivity, and very low leaching of palladium.