Ag/AgCl reference electrode wich is "homemade" from silver wire anodisated from 5 N HCl for 10 min. using a 1.5 V source. See also "Electrochemistry at solid electrodes", autor: R.A. Adams, edit. M. Dekker. Inc., N.Y., 1969

I am not agree with Tanta Spataru as if we will use silver paint as electrodes in order to apply the ac or dc voltage then how we can be sure that the small silver ions don't contribute to the conductivity of the sample? As we cannot tolerate the contribution to the conductivity from the small silver ions thus one must use platinum as electrode instead of silver.............Good Luck...............

I will suggest that calomel reference electrode is best for Aqueous systems

Ag/AgCl is one of the lowest cost reference electrodes available, either commercially or homemade. The problem is they're not very stable and should be used in a fritted tube with Ag saturated KCl to maintain the best performance and reduce the amount of AgCl dissolution in the reaction vessel. Even so they will drift over time and should be calibrated versus a known redox couple. We use ferrocine in my group. Saturated calomel (SCE) is slightly more expensive and really should be purchased commercially, though they offer much better stability, They should also be calibrated with ferrocine or a similar redox couple.