Combination of 4-probe impedance and polarization measurements offers an effective approach to investigate electrode kinetics and transport properties of each cell component in a solid-state electrochemical cell based on an electrolyte of mixed ionic-electronic conductor (MIEC). In particular, two representative solid-state cells, one with an electrolyte of an MIEC (Pt /BaCe0.8Gd0.2O3/ Pt) and the other with an electrolyte of an ionic conductor (Pt /Bi1.5Y0.5O3/ Pt), are used as examples to demonstrate the uniqueness of these techniques in separating the response of each cell component, in measuring the interfacial polarization resistance and overpotential of each individual interface, in identifying reaction mechanisms (the nature of rate-limiting steps), and in determining kinetic parameters.