The non-linear dependance of polarization impedance of a metal ECG electrode placed on the surface of a living biosample (toad) on current density, frequency, etc has been studied in terms of incremental linear lumped polarization resistance DELTA R//p and capacitance DELTA C//p by considering only the first order non-linearity. Experimental measurements of DELTA R//p and DELTA C//p have been performed with an incremental linear electrical bridge (modified Wein bridge) using small signal ac current density ( DELTA sigma //f) superimposed on dc current density ( sigma //n). From the experimental results, an approximate inverse relationship between the incremental linear polarization parameters DELTA R//p and DELTA C//p with the excitation frequency f has been found.