In this study, we demonstrate the synthesis of the hetero-dialkaline hexafluorosilicate red phosphor KNaSiF6:Mn4+ by etching Si wafers in a HF/KMnO4/NaMnO4 center dot H2O mixed solution. The X-ray diffraction analysis indicates that the synthesized phosphor has an orthorhombic structure with the space group D-2h(16)-Pnma. The luminescence properties of the phosphor are studied by photoluminescence (PL) analysis, PL excitation spectroscopy, and luminescence lifetime measurements, and are found to be intermediate of those of homo-dialkaline K2SiF6:Mn4+ and Na2SiF6:Mn4+ red phosphors. (C) 2011 The Electrochemical Society. [DOI: 10.1149/2.064202jes] All rights reserved.