The recent introduction of Parr’s 4878 Automated Liquid Sampler has allowed the construction of a complete system for activity/kinetic testing of catalysts in a high pressure, high temperature environment. In the system shown, a Parr 2280 Gas Burette with 50 mL reservoir delivers H2 at a user-settable, constant pressure to a 4566 300 mL stirred reactor. Operation at up to 180 bar at up to 350 °C is possible. A Parr XCAD (eXternal Catalyst Addition Device) allows introduction of solid/powder catalyst to the liquid contents of the reactor at reaction pressure and temperature, setting t=0 for kinetic experiments. An included gas entrainment impeller provides for high speed three phase mixing. A Parr 4878 Automated Liquid Sampler allows unattended collection of filtered liquid samples from the reactor at a user-defined interval for subsequent analysis.