Interfacial polarization in electrolytes or other ionic media is a well-known phenomenon in connection with the relative surface potential difference. The created space charge affects the distribution of charge carriers in an electrolyte itself similarly to the field effects in semiconductors. This results in a number of secondary effects, from dielectrophoresis to the varied conductivity of the media. Some of these effects, including dielectrophoresis, and electric field sensing in the electrolytes, are analyzed analytically, modeled numerically, and evaluated experimentally. The physical nature of the thermoelectric effect in gels and a totally ionic field effect transistor is revealed, and the correspondence to experimental data is demonstrated.