Thin films of V3Si were deposited on various substrates such as quartz, sapphire, graphite, but principally on MgO using the hydrogen reduction of the mixed chlorides. The evaporator used for the vapor phase control of the reduction process was designed to take advantage of the principle of steady state and therefore was able to yield films with very accurate chemical compositions. Thin films ranging in thickness from 100 000 Å down to 1000 Å were deposited on MgO at a temperature of approximately 1000°C. The transition temperatures of these films were as high as 16.7°K for the thick films, but as low as 14.85°K for the thin ones. The composition of the films was checked by x-ray diffraction and x-ray fluorescence analysis. The gross composition of the films was found to depend on the composition of the vapor and the substrate temperature. It is a well-known fact that thin films of soft superconductors smaller than the penetration depth are characterized by a higher critical field than the bulk. In order to check a corresponding size dependence in a hard superconductor such as V3Si, thin films of various thicknesses were produced with a fixed composition. The transition field of these films was measured at liquid-hydrogen and liquid-helium temperatures by a resistance method. The temperature dependence of the transition field was found to be linear for all films up to 105 kG and to be invariant with film thickness within the limits of experimental error. This behavior, which is very different in nature from that of a soft superconductor, can be interpreted in terms of the filamentary theory of hard superconductivity.