Icosahedral boron phosphide (B 12 P 2) is a wide bandgap semiconductor (3.35 eV) that has been reported to "selfheal" from high-energy electron bombardment, making it attractive for potential use in radioisotope batteries, radiation detection, or in electronics in high radiation environments. This study focused on improving B 12 P 2 hetero-epitaxial films by growing on 4H-SiC substrates over the temperature range of 1250-1450 • C using B 2 H 6 and PH 3 precursors in a H 2 carrier gas. XRD scans and Laue transmission photographs revealed that the epitaxial relationship was (0001) 1120 B 12 P 2 (0001) 1120 4H-SiC. The film morphology and crystallinity were investigated as a function of growth temperature and growth time. At 1250 • C, films tended to form rough, polycrystalline layers, but at 1300 and 1350 • C, films were continuous and comparatively smooth (R RMS ≤ 7 nm). At 1400 or 1450 • C, the films grew in islands that coalesced as the films became thicker. Using XRD rocking curves to evaluate the crystal quality, 1300 • C was the optimum growth temperature tested. At 1300 • C, the rocking curve FWHM decreased with increasing film thickness from 1494 arcsec for a 1.1 μm thick film to 954 arcsec for a 2.7 μm thick film, suggesting a reduction in defects with thickness.