We report lattice‐matched single‐crystalline dielectric films on a III–V compound semiconductor InP(001) substrate by molecular‐beam epitaxial growth of BaxSr1−xF2. We used two methods to grow mixed fluoride films: two separate beams of BaF2 and SrF2 as well as a single beam of BaxSr1−xF2. In situ reflection high energy electron diffraction shows the parallel epitaxial relationship, BaxSr1−xF2(001)∥InP(001) and BaxSr1−xF2[110]∥InP[110]. The films were studied by double‐crystal x‐ray diffractometry for lattice parameters and Rutherford backscattering/channeling for compositions and crystallinity. Transmission electron microscopy shows that the films are single crystalline. Preliminary electrical results are also mentioned. Lattice‐matched single‐crystalline dielectric films can be important for epitaxial metal–insulator–semiconductor as well as semiconductor–insulator–semiconductor structures in a variety of device applications.