Single crystals of 4.1% Cr3+ doped Cs2NaScCl6 were studied by variable temperature optical absorption and luminescence spectroscopy. The (4)A(2g)<----> T-4(2g) transition exhibits a great deal of fine structure both in absorption and emission spectra. The dynamic Txe Jahn-Teller effect in the Cr3+ T-4(2g) excited state is analyzed on the basis of the Ham quenching in the T-4(2g) spinor splitting and the vibrational fine structure in the 7 K T-4(2g)--> (4)A(2g) luminescence spectrum. The combined effect of the a(1g) and e(g) distortions leads to a net axial compression of the CrCl63- equilibrium geometry by 0.029 A, and an equatorial expansion by 0.088 A in the T-4(2g) excited state relative to the (4)A(2g) ground state. These results are compared to those from other Cr3+ doped chloride and bromide elpasolites, and their different room temperature luminescence quantum yields are discussed on the basis of their different T-4(2g) excited state distortions. Temperature dependent luminescence and lifetime measurements show that in Cr3+:Cs2NaScCl6 at room temperature the luminescence quantum yield is about 0.7. (C) 2001 American Institute of Physics.