The surface tension of ethyl fluoride (R161) was measured over the temperature range from (233 to 373) K with a differential capillary rise method, together with the surface tension of isobutane (R600a) measured in the temperature range from (275 to 343) K for verifying the experimental system. The temperature and surface tension uncertainties were estimated to be within +/- 20 mK and +/- 0.2 mN m(-1) respectively. The surface tension values of R161 were correlated as a function of temperature with an average absolute deviation of 0.043 mN m(-1). (C) 2011 Elsevier B.V. All rights reserved.