CaAlSiN3:Eu2+ fine powder phosphors were successfully synthesized from the fully oxidic system CaO/Al2O3/SiO2 using the gas-reduction-nitridation (GRN) method. The GRN reaction was conducted at low temperatures of similar to 1370 degrees C to obtain nitrided precursor powders that could be converted into nearly single-phase CaAlSiN3 by a moderate heat treatment at 1600 degrees C for 4 h in a N-2 atmosphere of 0.92 MPa. Highly efficient CaAlSiN3:Eu2+ red-emitting phosphors were obtained using a fluoride activator, with external quantum efficiencies of up to 72%.