We have studied the behavior of a chemically synthesized polypyrrole as electrode material. The different electrochemical methods that we have used for this characterization, namely, cyclic voltammetry, ac impedance measurements, and cyclic chronopotentiometry, have evidenced the role of the low frequency capacitance Cnormals characteristic of the doped state of polypyrrole. This capacitance seems independent of the synthesis conditions of the polymer, and we show that it partially explains the large value of the total charge false(Cnormalm>100 normalAh/normalkgfalse) stored in this polypyrrole. Analyzing the effect of residual water in the polymer, we show that a water content of about 3% (w/w) increases the total charge Cnormalm and lowers the redox potential E0 . A quasi linear relationship has been found between E0 and Cnormalm , the massic capacity: Cnormalm increases when E0 decreases. This relation can be also attributed to the charging of the capacitance Cnormals:Qnormalcs=Cnormals false(Enormald−E0false) , where Enormald is the degradation potential. We discuss the origin of this capacitance Cnormals .