In order to obtain new scintillators with high light output and high effective atomic number (Z(eff)), we performed anion-substitution for Cs2HfCl6 (CHC) scintillator, and then, we succeeded in growing Cs2HfI6 (CHI) single crystalline scintillator. It had Z(e)n of 58, which is the same as that of CHC, and had high light output of similar to 70,000 photons/MeV with 700 nm emission. However, its scintillation decay time of similar to 2.5 mu s was slow for practical use as gamma-ray monitor. In this study, we performed Ce3+/Eu2+ doping to Hf4+ site to improve decay time of CHI, introducing the fast 5d-4f luminescence. Ce:CHI and Eu:CHI single crystals were finally obtained by the vertical Bridgman-Stockbarger method. The luminescence spectra of the Ce:CHI and Eu:CHI were very similar to that of the non-doped CHI, which would mean that no 5d-4f luminescence of Ce3+/Eu2+ was observed. The measured light output and decay time of Ce:CHI were similar to 48,000 photon/MeV and 2.3 +/- 0.1 mu s, respectively. As for Eu:CHI, light output and decay time were similar to 69,000 photon/MeV and 2.8 +/- 0.1 mu s, respectively. (C) 2018 Elsevier B.V. All rights reserved.