An electrolytic cell consists of two electrodes, one electrolyte, and a power source.

The chemical principles that apply to the operation of a voltaic cell also apply to an electrolytic cell. The strongest oxidizing agent undergoes reduction at the cathode and the strongest reducing agent undergoes oxidation at the anode. However, some important differences exist between a voltaic cell and an electrolytic cell.

In an electrolytic cell, electrons are supplied from an external power source. The cathode (where reduction occurs) is attached to the negative terminal of the power source and is designated as the negative electrode. Conversely, the anode is attached to the positive terminal and is designated as the positive electrode. Recall that the electrodes were designated opposite to this in a voltaic cell.

In an electrolytic cell, the reaction is non-spontaneous; therefore, the net cell potential is negative.

The electrolytic cell can be represented by the following notation:

\( \mathrm { anode~|~ electrolyte~ |~cathode } \)

Note that no double line is used because no porous boundary occurs in an electrolytic cell. Rather, the electrolyte is in constant contact with both electrodes.