We performed an in-depth electrochemical study on the ion-blocking electrochemical cells Pt/Li-1/2(Ln(x)La(1/2-x))TiO3/Pt (Ln = Nd, Gd) over a wide frequency, impedance magnitude, and temperature range, and proposed an equivalent circuit which is original in its low frequency interpretation. The electrical properties of the bulk and the grain boundary were analyzed closely in relation to the crystallography and the characteristic microstructure of the system.