New solid solutions of A(1-x)Li(2x)BO(4) (A = Ca, Sr or Ba, B = W or Mo) with a scheelite-type structure were synthesized and the lithium ionic conduction were confirmed by electrochemical measurements and neutron radiography (NR). Irrespective of A-site cations, the conductivities for molybdates were higher than tungstates. The highest conductivity was observed at the composition of x = 0.05 in each system. NR analysis showed that, the lithium ion conduction would be ascribed to interstitial lithium ions in Ca0.95Li0.1MoO4, although the fairly big lithium ion diffusion due to thermal effect was observed.