In this paper, we synthesized a novel yellowish orange phosphor, Eu2+-doped high-temperature phase (HTP) Ca3SiO4Cl2 at 1020 degrees C. The primary crystal structure of HTP-Ca3SiO4Cl2 is determined as monoclinic structure with a space group of 14 P21/c. The excitation spectrum of Eu2+-doped HTP-Ca3SiO4Cl2 exhibits a broad-band between 250 and 500 nm with three peaks of around 327, 371, and 426 nm, which are coupled well with the near-UV (n-UV) or deep blue emission of GaN-based light-emitting diodes (LEDs). Its emission spectrum shows a single intense broad emission band centered at 572 nm. The measured chromaticity of yellowish orange luminescence is x = 0.52, y = 0.45. Eu2+-doped HTP-Ca3SiO4Cl2 would be suitable for yellowish orange phosphor of white LED because HTP-Ca3SiO4Cl2: Eu2+ is excellent in the excitation spectral profile and the chromaticity. (c) 2005 The Electrochemical Society. All rights reserved.