In this article, we report the development of a cell setup which can be used to cycle ASS-FIBs at extended pressure up to 2 GPa and temperatures up to 200 °C. This cell was then used for a detailed investigation of the conductivity of four common solid fluoride ion conductors (Ba0.6La0.4F2.4, La0.9Ba0.1F2.9, BaSnF4 and PbSnF4) under pressure, with an analysis of the activation volume of the electrolytes at their respective operation temperatures of 170 °C and 30 °C. We show that the application of pressure has a strong impact on the cyclic stability of For operation of all-solid-state batteries under pressure, a hot-press was constructed. A rendering of the design is shown in Figure . The design includes space for a hydraulic cylinder to apply force on the cell pellet. The cylinder presses onto a holder for disc springs which are used to minimize the force changes due to volume change of the pellet during cycling. This spring holder sits in a steel alignment part with a PTFE liner to electrically insulate the steel pins from the steel frame. Inside the alignment part, the steel pins are split to incorporate a 3 mm thick alumina disc to allow for insulation in the axial direction as well. The current collector pins are exposed to allow connection of a potentiostat via crocodile clamps. While the entire frame is made of mild steel, the current collector pins are made from 1.2343 hot working steel (equivalent to AISI H11), to avoid plastic deformation up to temperature of 200 °C. Both current collector pins meet inside another steel mantle for alignment, which is lined by a PTFE tube for electrical insulation. Optionally, to increase the range of applicable pressure, the pins diameter can be reduced from 7.5 mm to 3.5 mm on the electrolyte contacting side. In this case, another alignment ring, made of PEEK with an inner diameter of 3.5 mm is placed around the smaller diameter tips of the current collector pins. PEEK was chosen over PTFE despite its lower chemical stability since it is much harder and avoids powder spill outs at high pressures. This steel mantle is sized to fit a 25 mm diameter heating band for high temperature operation of the cells. Around the steel mantle there is ample space to fit the heating mantle, a thermocouple, the crocodile clamps for electrical contact and ceramic fiber insulation. On the bottom of the hot press, below a second alignment part with PTFE liners and split pins for accommodation of an alumina disc, a force transducer is placed to monitor the applied force on the pellet. The output signal of the force transducer, a voltage which is proportional to the applied force, is amplified using a LM358N operational amplifier, read by an Arduino UNO and sent to a PC using serial communication where a python script is used to display and save the data. The amplification circuit can be found in the Supporting Information (Figure S 1), while the python script and the code to be run on the Arduino are also provided in the Supplementary Material.