Monophasic KLaF4 possessing cubic symmetry with varied Eu3+ concentrations were synthesized by wet-chemical reaction. The obtained nanophosphor exhibits nanocrystals of 5 nm size and the dopant Eu3+ ions were successfully incorporated into the sites of La3+ ions of the host lattice. The dominant red color emission at 612 nm from the hypersensitive (D-5(0) -> F-7(2)) transition of Eu3+ indicates the inversion anti-symmetry crystal field around Eu3+ ion, which is favorable to improve the red color purity. Furthermore, the emission life times are high enough and our results broadly suggest the potential application for white LEDs, mercury-free lamps and display panels. (C) 2011 Elsevier B. V. All rights reserved.