Must likely you cannot. The problem is the control systems. The potentiostats will "fight" each other and unwanted results can follow. However, if one of the potentiostat has the option of "floating" you might be able to do it. 

I would recommend that you tweek your setup instead. Let the two potentiostats share the same reference electrode, but use two counter electrodes and two working electrodes. That way, it might still work.

Good luck.

As Gustav said, this is a tricky issue.  You should contact the manufacturer of your potentiostats for their advice on configuring two potentiostats to function as a bipotentiostat..

Being not an electronic engineer I would try it as Long as the working electrode is set to the circuit ground and you have two reference electrodes and two auxiliary electrodes to be connected to the two potentiostats of the same kind.

I got this to work if one of the two instrument is a floating potentiostat. I could even share counter and reference electrodes.

If both potentiostats are grounded, it did not work even using two completely separated sets of electrodes (i.e. two three-electrode setups).

As far as I could see it is possible and basically the trick is that at least one of the potentiostats has to be floating. However, it does not work with all potentiostats, for example I used an Autolab as grounded potentiostat and an Ivium as floating one and it did not work well. Substituting the Autolab with a very old Sycopel solved the problem.

I noticed that if it works you can share reference and counter electrodes, but I am not sure this is generally true.

Another problem comes if you want to acquire data from both potentiostats. Then you need to read differentially from both of them to avoid to indirectly ground them through the acquisition devise.

As for data acquisition per Alberto's comment, a potentiostat that allows for data transfer via Bluetooth is an option (e.g. PalmSens). If it's a USB data transfer, purchasing a USB isolator may provide the needed isolation.

You can also use potentiostats without galvanic isolation and exploit the fact that the WEs are on virtual ground. This will only allow you to perform the same experiment with both electrodes, because one electrode is just a passive current follower. More about that here: https://www.palmsens.com/wp-content/uploads/2021/02/PSAN0408-MPS4-synchronized-measurements-with-the-MultiPalmSens4.pdf

what's the name of that "fight" or issue connection between two potentiostats? I have the same problem with a potentiostat and a ZRA connection but I don't know the technical name of the problem.

Hi E.C. Hornus ,

short answer: the term is "ground loop".

Long explanation: the "fight" is connected with the fact that usually a potentiostat places the working electrode at ground or virtual ground. When you connect two working electrodes coming from two potentiostats in the same cell then you have two grounds points (or virtual grounds) and two control loops trying to arrange the other electrodes against them. The result is either no control (unstable behaviour, overload etc.) or a ground loop which may be in action without really giving strange signs in the instruments.

As stated one possibility is to have a potentiostat in floating mode that is galvanically isolated from any other device.

Note that ground loops can happen not only between potentiostats but in general between any device either through the power cord or through BNC or any other signal connection. I think this is your issue.