New red Ca10K(PO4)(7):Eu3+, K+ phosphors were synthesized by solid state reaction and their photoluminescence properties as well as those by co-doping Mo6+ under near ultraviolet excitation were investigated. From the excitation spectra monitored at 611 nm, it can be seen that the strongest excitation peak is situated at 393 rim, well matching with the emission wavelength of near-ultraviolet chips for white LEDs. Upon 393 nm excitation, the brightness of Ca9K(PO4)(7):0.5Eu(3+), 0.5 K+ with the optimal Eu3+-doping concentration is about 2.3 times stronger than that of the commercial red Y2O3:Eu3+ phosphor. The introducing of Mo6+, which results in a possible variety for the excited energy level of the host, can enhance the brightness of Eu3+ to be maximized by about 15%. The CIE chromaticity coordinates of Ca9K(PO4)(7):0.5Eu(3+), 0.5 K+ are calculated to (0.654, 0.345), which are close to the (0.67, 0.33) standard of the National Television System Committee. All the above results indicate Eu3+-activated Ca10K(PO4)(7) is a potential candidate for white LEDs. (C) 2011 Elsevier Ltd. All rights reserved.