We study the current-voltage characteristics of contact glow discharge electrolysis in alkaline medium, upon increasing and decreasing-step voltage sweeps. Two levels of configurational states are identified: a global N-shaped negative differential resistance, with an embedded S-shaped behavior in a hysteresis loop around the critical voltage the voltage at which the system switches its behavior from conventional electrolysis to glow discharge electrolysis. The S-shaped nonlinearity is attributed to the dynamic self-assembled space charge system formed by the gas film on the one hand, and the glow-emitting electrode on the other hand, and acts as a parasitic energy storage element. Electrical models for the current-voltage behavior based on tanh(x) nonlinearity are presented and discussed. (C) 2015 Elsevier Ltd. All rights reserved.