Y-stabilised zirconia (YSZ) thin films have been grown by pulsed laser (KrF) deposition on (100)InP substrates at temperatures compatible with current InP processing techniques. The cubic YSZ phase has been obtained heating the substrate in the 550–600°C range. The optimal deposition pressure was found about 10−5 mbar and the deposition rate was 0.07–0.lÅ/pulse. The films deposited after a substrate treatment in vacuum show the following epitaxial relationship 〈100〉{100}YSZ‖〈100〉{100}InP. The full-width at half-maximum of the X-ray diffraction from the film decreases with film thickness up to a minimum of 1.6°. The average film roughness in defect-free areas is about three YSZ lattice units (1.4nm) for 225 nm thick films and the refractive index is similar to that measured in bulk YSZ crystals. Increasing the deposition pressure above the optimal leads to non-cubic YSZ, due to the Y loss.