Lanthanum-lithium-sodium double chromates Li1-xNaxLa(CrO4)(2) were prepared and analysed by means of admittance spectroscopy. Their a.c. conductivity parameters are correlated with structural details of high and low temperature forms of pure lanthanum-lithium double chromates. Lithium compounds show the lowest conductivity values and the highest activation energy for ion motion, while the sample Li0.5Na0.5La(CrO4)(2) exhibits the highest conductivity 10(-5) S cm(-1) and the lowest activation energy 0.58 eV.