If you are performing electrolysis at long time, two electrodes are enough. However it depends on the information you would have.

Generally at lab reactor, you should use a reference electrode to haver a better control/understanding of what is going on. On the other hand, when you are using high volume reactors, the reference electrode won't work accurately, then you can use a two electrodes system.

I don't know if this response helps you.

For further information, only ask.

" I am working with two electrode system (both electrodes of same material)..." Are you working on electrorefining?

You may use a constant current source with a two electrodes cell. Choose/find the optimal current density.

Use a common lab reference electrode to measure/monitor the potential of working electrode and the potential of the counter electrode. The sum of the two potentials is the applied voltage. You may use a common voltmeter (minimum input impedance 10 Mohm).

@Jordi:

Why do you think that with " high volume reactors, the reference electrode won't work accurately"? I tried such a measurement in an electrorefining installation (6000 L: 3 series of 6x330 L cells, in parallel). The trick is to place the reference electrode close to the working/measured electrode.

Cornel

With high Volume reactor, you should use high surface electrodes and, generally, in these systems the current distribution is no constant and, consequently, the potential you measure with the reference electrode may not be so accurate.

Generally in lab investigations it is a MUST to use an reference elctrode also. So three electrode system is necessary.

Thanks all for the suggestion. I think I should try with both two and three electrode system and compare the results.

i guess 3 electrode system would be the ideal one at it will lead to a better information than the two electrode system.