Scheelite type solid electrolytes, Li0.5Ce 0.5-xMoO4 (x = 0 and 0.25, Ln = Pr, Sm) have been synthesized using a solid state method. Their structure and ionic conductivity (s) were obtained by single crystal X-ray diffraction and ac-impedance spectroscopy, respectively. X-ray diffraction studies reveal a space group of I41/a for Li0.5Ce0.5-xMoO4 (x = 0 and 0.25, Ln = Pr, Sm) scheelite compounds. The unsubstituted Li 0.5Ce0.5MoO4 showed lithium ion conductivity ̃10-5-10-3 Ω-1cm-1 in the temperature range of 300-700°C (σ = 2.5×10-3 Ω-1cm-1 at 700°C). The substituted compounds show lower conductivity compared to the unsubstituted compound, with the magnitude of ionic conductivity being two (in the high temperature regime) to one order (in the low temperature regime) lower than the unsubstituted compound. Since these scheelite type structures show significant conductivity, the series of compounds could serve in high temperature lithium battery operations. © Indian Academy of Sciences.