Different types of instruments have been developed both for in-pile fuel and materials studies at the Halden Reactor Project. In recent years, several of the standard instruments have been upgraded to be able to tolerate much higher temperatures. In particular, several instruments are now able to operate up to 650°C and 25 MPa, thus in the range suitable for supercritical water (SCW) studies. In addition, a feasibility study for an in-pile SCW loop has been carried out that shows that such a loop can be realized in the Halden reactor, allowing for all the instrumentation possibilities that are presently carried out in pressurized water reactor (PWR) and boiling water reactor (BWR) conditions. Another, and cheaper, alternative is to perform corrosion experiments inside a small capsule in which SCW is maintained by means of gamma heating and external pressure lines. The conceptual designs of the SCW loop and SCW capsule will be highlighted.