Abstract An internally pressurized aerostatic journal bearing suitable for thermoacoustic power converters is designed and experimentally demonstrated using a free piston oscillating in a cylinder between two gas springs. The oscillating pressures in a thermoacoustic power converter׳s cavities can be used to create a near constant flow through an air gap between piston and cylinder. By selectively supplying and draining gas from gas reservoirs to the converter׳s gas cavities, separate reservoirs inside the piston can be maintained below and above the engine mean pressure. A continuous flow of gas between these reservoirs in the air gap creates an aerostatic gas bearing between the converter׳s piston and cylinder. The results show that, under the operating conditions of thermoacoustic power converter, a robust passive gas bearing is feasible.