Three electroanalytical techniques have been used to study the solid-state ionic diffusion of lithium into cerium–vanadium mixed oxide thin films, i.e. potentiostatic intermittent titration technique, galvanostatic intermittent titration technique and electrochemical impedance spectroscopy. Diffusion coefficients measured with the above mentioned techniques show a non-monotonic decay between 8×10−12 and 8×10−14 cm2 s−1. In particular, lithium diffusion coefficient drops by more than one order of magnitude at lithium intercalation degree x=0.6. This abrupt change seems to be related to a dramatic increase of the material resistance suggesting that the limiting factor in atomic lithium diffusion may be the low electronic conductivity.