Photoluminescent spectra have been recorded for Cs2NaY1-xErxCl6 at room temperature (RT) and 10 K using synchrotron radiation. Striking differences are observed between RT and 10 K emission spectra. First, unusual quenching of emission from a higher energy level ((4)G(11/2)) at RT leads to dominant visible emission at 10 K from a lower one (S-4(3/2)). Second, emission from (2)G(9/2) is not observed at RT but appears at 10 K. Third, the red emission from F-4(9/2) is much weaker at 10 K. Cross-relaxation quenches emission from multiplets D-4(5/2) and F-4(5/2) in Cs2NaErCl6 whereas emission from the former is clearly observed in dilute Cs2NaYCl6:Er3+. Detailed assignments are provided and the cross-relaxation processes are described. (C) 2011 Elsevier B.V. All rights reserved.