The CaSe1-xSx:Eu phosphor, prepared by a wet-chemical method, emits visible light from reddish orange to red due to the f-d transition of Eu2+ ions. Their emission bands are found to be shifted by sulfur substitution in the selenium sites, and such a substitution was found to influence the crystal field of surrounding Eu2+ ions through a reduction of the lattice parameter. These phosphors are promising candidates for emitting red light for light-emitting diodes (LEDs). When mixed with a green phosphor on a InGaN-based blue chip, the as-synthesized red phosphors generated white light for LEDs. (c) 2006 The Electrochemical Society.