Sm2Mo2O3.83N3.17, the first molybdenum oxynitride pyrochlore. was synthesized by heating the Sm2Mo2O7 pyrochlore in flowing ammonia at 625 degreesC for 24 hours. Sm2Mo2O3.83N3.17 forms with the cubic pyrochlore structure, space group Fd3m (a = 10.4975 Angstrom). The sample is semiconducting and the temperature-dependent magnetic susceptibility follows Curie-Weiss behavior. X-ray absorption near-edge spectroscopy measurements indicate that in the oxynitride, molybdenum has a formal oxidation state significantly larger than 4 +.