A process for synthesizing a color stable Mn 4+ doped phosphor includes contacting a precursor of formula I, I, II, III or IV is contacted with a fluorine-containing oxidizing agent in gaseous form at an elevated temperature to form the color stable Mn 4+ doped phosphor A a B b C c D d X x :Mn4+ (I) A ai B bi C ci D d X x Y d :Mn 4 + (II) A 1 3 G 2m-n Mn m Mg n Li 3 F 12 Q p, (III) AZF 4 :Mn 4+ (iv) wherein A is Li, Na, K, Rb, Cs, or a combination thereof; B is Be, Mg, Ca, Sr, Ba, or a combination thereof; C is Sc, Y, B, Al, Ga, In, Tl, or a combination thereof; D is Ti, Zr, Hf, Rf, Si, Ge, Sn, Pb, or a combination thereof; X is F or a combination of F and at least one of Br, CI, and I; Y is O, or a combination of O and at least one of S and Se; A1 is Na or K, or a combination thereof; G is AI, B, Sc, Fe, Cr, Ti, In, or a combination thereof; Z is La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc, Y, In, or a combination thereof; 0