A TS-1 catalyst layer has been coated inside a capillary microreactor by the transformation of a porous silica precoating using an in-situ hydrothermal synthesis method. The use of the silica precoating to favour TS-1 nucleation and growth on the microchannel surface has shown to provide a final TS-1 coating of high surface area and titanium loading with good stability. The ability to transform the silica precoating to a TS-1 coating was achieved by correctly balancing the silica precoating dissolution, zeolite nucleation and growth rates, and insertion of titanium into the zeolite framework. The 4 mu m TS-1 coating, consisting of TS-1 crystals of approximately 800 nm in size, was applied in the epoxidation of propene as a model reaction to demonstrate its catalytic activity. The TS-1 microreactor obtained a propylene oxide productivity of 2 g(PO)/g(cat) h with a propylene oxide selectivity above 90%. Long-term stability tests of the TS-1 microreactor showed that the TS-1 coating is very stable with only a small deactivation noted over a 500 h time-on-stream period. (C) 2014 Elsevier B.V. All rights reserved.