A fibre optical displacement transducer for high temperature applications was manufactured. The transducer is based on in-fibre Bragg gratings that are embedded in a transducer body made of Inconel. The fibre embedding is done by vacuum brazing at a temperature of 950ºC using a silver based brazing alloy. This technique solves many problems in constructing the transducer. During the brazing process the brazing material forms an alloy together with the metallic coating on the fibre. Because of this and the low thermal expansion of the silica the fibre will end up in axial and radial compression when the alloy around the fibre solidifies and cools down. The life of an optical fibre is limited by crack growth initiated by tensile stress; it is therefore an important advantage to have the fibre in compression rather than in tension. Further, the compression will reduce upon re-heating the transducer to the service temperature. This minimizes the risk of fibre slipping inside the embedding. The embedded fibre is also hermetically protected from moisture (causes stress corrosion) and effective strain and temperature transfer to the fibre is ensured. The displacement is measured by deflecting a beam in which the fibre is embedded. Because the in-fibre Bragg grating is embedded off the neutral line of the beam the Bragg grating is either compressed or stretched depending on the direction of deflection. The displacement is determined from the wavelength of the light reflected from the Bragg grating. Intended applications are materials testing in simulated nuclear reactor environments and even in supercritical water environment at temperatures up to 600ºC. The geometry of the transducer can easily be modified for different applications.