A buffer is a solution containing either a weak acid and its salt or a weak base and its salt, which is resistant to changes in pH. The buffer capacity concept is extended on dynamic redox systems, realized according to titrimetric mode, where changes in pH are accompanied by changes in potential E values;( +ve or –ve E values) it is the basic novelty of the paper. Two examples of monotonic course of the related curves of potential E vs. Φ and pH vs. Φ relationships were considered. The systems were modeled according to GATES/GEB (Generalized Approach to Electrolytic Systems)/(Generalized Electron Balance) principles.