A new method for the preparation of phase-pure ferromagnetic Fe3P films on quartz substrates is reported. This approach utilizes the thermal decomposition of the single-source precursors H2Fe3(CO)9PR (R = tBu or Ph) at 400 °C. The films are deposited using a simple, home-built metal-organic chemical vapor deposition (MOCVD) apparatus and are characterized using a variety of analytical methods. The films exhibit excellent phase purity, as evidenced by X-ray diffraction, X-ray photoelectron spectroscopy, and field-dependent magnetization measurements, the results of which agree well with measurements obtained from bulk Fe3P. Using scanning electron microscopy and atomic force microscopy techniques, the films are found to have thicknesses between 350 and 500 nm with a granular surface texture. As-deposited Fe3P films are amorphous, and little or no magnetic hysteresis is observed in plots of magnetization versus applied field. Annealing the Fe3P films at 550 °C results in improved crystallinity as well as the observation of magnetic hysteresis.