Materials with redox properties have been widely used in sensing applications. Understanding the redox properties of these materials is an important issue. In order to investigate the redox properties, there are several methods, such as using the Kelvin probe and a conductivity sensor, or using other well-known electrochemical techniques. In this paper, we introduce another possibility to characterize redox materials by investigating their work function using an electrolyte metal-oxide semiconductor field effect transistor (/sup E/MOSFET) device, in which the studied redox material is applied as gate electrode. In the /sup E/MOSFET, the conductivity of the channel is modulated by the work function of the studied material. The change in the work function of a redox material due to electrically and chemically induced processes will be shown by an example of the /sup E/MOSFET having a potassium ferric ferrocyanide gate.