The viscosity of gaseous HFC245fa (1,1,1,3,3-pentafluoropropane) was measured at the temperature range from (300 to 396) K and pressures up to 1.6 MPa. The measurements were carried out in ail oscillating disk viscometer of the Maxwell type, and the measurements were relative to the viscosity of nitrogen. The uncertainty of the reported viscosities was estimated to be within +/- 2.0 % with a coverage factor of k = 2. The measured data were correlated as a function of temperature and density with a maximum deviation of 0.53 % and ail absolute average deviation of 0.21 %.