The paper describes an improved Maxwell type oscillating-disk viscometer. The experimental system was calibrated by argon, carbon dioxide, nitrogen, hydrogen and verified by nitrogen. The viscosities of gaseous HFC-161 were measured from 293 K to 369 K at pressures from 0.1 MPa up to the saturated vapor pressure. An empirical viscosity equation is proposed to interpolate the present experimental data as a function of density and temperature. The uncertainty of the reported viscosity was estimated to be within 1%. (C) 2014 Elsevier B.V. All rights reserved.