The investigation of processes of ischemia in different organ tissues is very important for the development of methods of protection and preservation during surgical procedures. Electrical impedance spectroscopy was used to distinguish between different tissues and their degree of ischemia. We describe mathematical methods used to adjust experimental data to Cole-Cole models for one-circle and two-circle impedance loci and a study of the main parameters for representing the behavior of ischemia in time. In vivo and in situ postmortem measurements of different tissues from pigs are shown in the 100 Hz to 1 MHz range. The Cole parameters that best characterize the ischemia are R0 and fc.