Highly efficient Sr2Si5N8:Eu2+ red emitting phosphor was successfully synthesized by a cost-effective direct silicon nitridation and gas-reduction method. The effects of synthesis parameters, including reaction temperature, heating rate and gas species, on the crystal structure and photoluminescence of the prepared phosphors were studied. Single-phase Sr2Si5N8:Eu2+ phosphor was obtained at 1500 oC with a heating rate of 300 oC/h under NH3-1 vol.%CH4 atmosphere using starting silicon and oxide powders. Silicon powder and high heating rate favored the achievement of the pure Sr2Si5N8 phase. Under near-UV to blue light excitation, the obtained Sr2Si5N8:Eu2+ phosphor showed a board red emission band centered at about 625 nm, which agreed well with the phosphors prepared by the conventional solid-state reaction. The possible reaction mechanism was also proposed based on the experimental observations. Highly efficient Sr2Si5N8: Eu2 + red emitting phosphor was successfully synthesized by a cost-effective direct silicon nitridation and gas-reduction method. The effects of synthesis parameters, including reaction temperature, heating rate and gas species, on the crystal structure and photoluminescence of the prepared phosphors were studied. Single-phase Sr2Si5N8: Eu2 + phosphor was obtained at 1500 oC with a heating rate of 300 oC / h under NH3-1 vol.% CH4 atmosphere using starting silicon and oxide powders. Silicon powder and high heating rate favored the achievement of the pure Sr2Si5N8 phase. Under near-UV to blue light excitation, the obtained Sr2Si5N8: Eu2 + phosphor showed a board red emission band centered at about 625 nm, which agreed well with the phosphors prepared by the conventional solid-state reaction. The possible reaction mechanism was also proposed based on the experimental observations