Measurements of the viscosity of liquid trifluoroiodomethane (CF3I) are reported over the temperature range from 253 to 338 K along the saturation line made with a calibrated capillary viscometer. An improved method was developed for calibrating the viscometer and measuring the viscosity. The uncertainty of the results is estimated to be no more than +/- 3%. The results were correlated as a function of temperature.