The phase diagram of the pseudobinary KNbO3–KVO3 system was determined by DTA and KNbO3 films have been grown for the first time on KNbO3, KTaO3, SrTiO3 and spinel substrates by liquid phase epitaxy from a K2O–V2O5 flux. Preliminary results on the fabrication of microstructures for rib waveguide applications by wet chemical and reactive ion etching of KNbO3 are reported.