Saturation of a liquid with gas before perfusing a tissue or cellular preparation under pressure can be achieved by bubbling the gas through the liquid. A container for this purpose that is housed in the pressure chamber with the preparation allows saturation of the liquid under hyperbaric conditions. Sealing the container allows saturation with a gas different from the gas used to compress the pressure chamber. If the pressure within the sealed container is maintained at a slightly higher level, the bubbling gas can also provide the driving force for the liquid to flow to the preparation. Based on this concept, an apparatus was built and tested to pressures of 6.8 MPa. This paper describes the saturator and the associated circuitry used to control bubbling gas pressure relative to the pressure vessel, gas flow through the saturator, and liquid flow to the preparation. A special application in the case of hydrogen gas is described, where this system has added safety advantages.