At present, piston and membrane compressor units in the range of medium and high pressure (3.0–10.0 MPa and more) and low productivity (0.001–0.03 m3/s) retain their competitiveness. Their technical characteristics can be improved in many ways, for example, by using long stroke stages. In one such stage, the gas pressure can be increased from 0.1 to 3.0–11.0 MPa without exceeding temperature limits. One of the research directions of such stages is to determine the most efficient thermal mode of operation of the stage. A ‘quasi-isothermal’ working process of compression with intensive external cooling of the cylinder and a ‘quasi-adiabatic’ working process of compression without intensive external cooling of the cylinder are considered as possible options. The article presents the results of a theoretical assessment of the effectiveness of the use of cooling and recovery systems in compressor units based on long-stroke piston stages. The possibility of providing a mode where the discharge gas temperature differs from the gas temperature at suction by 40–80 K is shown. This should be considered a good achievement for the 30–100 ratio of the discharge pressure to the suction pressure. A theoretical possibility of increasing the discharge temperature up to 500–900 K is shown, which makes it possible to effectively apply the heat recovery system of compressed gases based on the Rankine cycle.