The paper describes the design and construction of a two cylinder apparatus to measure heat transfer under conditions of oscillating pressure and oscillating flow such as found in Stirling-cycle machines. The apparatus consists of two large single stage air compressors joined by a rigid drive shaft between the two crank shafts. The compressors are 27.94 cm (11-in) diameter by 22.86 cm (9-in) stroke. The apparatus is powered by a 25 HP variable speed DC motor. Belts and a jack shaft provide wide speed ranges. The test section, which is connected between the compressor cylinders, is a 44.45 mm (1.75-in) diameter tube and about 254 cm (100-in) long. The test section is configured for measuring wall heat flux, and gas pressure as a function of time. An LDV system is being installed for measurement of gas velocity as a function of time and position. A fast response micro thermocouple measures gas temperature as a function of time and position. A PC based data acquisition system is used for control of the experiments. The apparatus is capable of measuring heat transfer while velocity and pressure are changing over the range of dimensionless parameters normally found in Stirling cycle machines. The independent variables of the apparatus are: gas molecular weight, average gas pressure, angular speed, phase angle between crank shafts and clearance volume in each compressor cylinder. The piston rod end of each compressor cylinder (compressors are double acting) is connected to a large bounce volume to pressure balance the average pressure during the test. Preliminary data from the apparatus are included in this paper.