Mn-doped ZnS has been studied as a yellow-orange phosphor for the application to fluorescent displays operated at low-excitation energies. It was found that under low-excitation energies (30 eV), the change of luminescence intensity of ZnS: Mn was nearly invariable after second firing or acid treatment of the phosphor. It seems that there is an exchange between conductivity of the phosphor, which is originated from a carbon-induced layer on the phosphor, and the increase of luminescent volume of the phosphor. The luminescence of ZnS: Mn phosphor is affected by addition of conductive material, such as In2O3, under low-excitation energy and high current density regime. (C) 2004 The Electrochemical Society.