In this investigation, thermo-viscoplastic behaviour of austenitic steel AISI 304 has been characterised in tension under wide ranges of strain rate at room temperature. This metal possesses an elevated strain hardening rate and ductility which enhance its capability for absorbing energy under mechanical loading. It has been observed that the rate sensitivity of the material is independent of plastic strain. Moreover, it has been noticed that beyond a certain level of loading rate the flow stress of the material sharply increases. In agreement with experimental evidences reported in the literature, this behaviour is assumed to be caused by the drag deformation mode taking place at high strain rates. Based on such considerations, the thermo-viscoplastic behaviour of the material has been macroscopically modelled by means of the extended Rusinek-Klepaczko model to viscous drag effects. Satisfactory matching has been found between the experiments and analytical predictions provided by the constitutive relation.