This paper presents results concerning the experimental investigation of a five-stage prototypical axial-flow microturbine operating in an ORC installation. The microturbine has an electrical capacity of 3 kW at the nominal rotational speed of 12000 rpm and is supplied with a low-boiling medium's vapour HFE7100. During the test, both the full vibration frequency distribution and the overall level of the velocity vibrations RMS in the microturbine were measured. A spectral analysis of vibration velocity was conducted during the grind-in process after a modernisation of the shrouding bandage of the microturbine set's flow system took place. The article presents the operational characteristics of the ORC system as well as the characteristics showing the electric power produced as the function of rotational speed of the microturbine. On the basis of the results obtained, there was assessed the dynamic performance of the microturbine and it was ranked according to ISO 10816-1 standard. The paper also shows the measurement results of the so-called kurtosis within the frequency range of 15 to 30 kHz, which made it possible to evaluate the dynamic state of the rolling bearings by which the microturbine's rotor was supported.