Experimental studies of change in the air temperature in a power unit with a prototype RPD-4.4/1.75 rotary-piston pneumatic motor were carried out to solve the problem of the negative impact of low temperatures of exhaust air on the pneumatic motor performance. It has been established that an increase in rpm by 62 % leads to a drop of air temperature after reducer by 33 %. In this case, the maximum temperature drop during throttling is 21 K under conditions of maximum rpm and pressure of 0.8 MPa in the inlet receiver. It was found that under experimental conditions, the average differential Joule-Thomson effect is in the range of 0.8…3.9 K/MPa when throttling in the reducer for the pressure range of 0.4...0.8 MPa in the inlet receiver. It was found that the temperature drop caused by air expansion in the working cylinder of the pneumatic motor is about 22 K in absence of regulation of the filling degree. At the same time, temperature fluctuations do not exceed 4.5 % depending on the change in the motor rpm and pressure in the inlet receiver. A maximum temperature decrease in the power unit was obtained experimentally. Under the experimental conditions and depending on the study mode, the temperature drop from the initial storage value is from 35 to 43 K. It was found that the amount of energy required for heating air at the inlet to the inlet receiver with a pressure of 0.6 MPa in the air storage temperature range of –5...–20 °С is 0.14...1.99 kW. In this case, the ratio Q p /N e can reach 0.1...0.58, that is, in some operating modes, more than half of the produced power will actually be spent on air heating. Accordingly, the results obtained are useful and necessary when choosing conditions and operating modes of the pneumatic motor