The thermal conductivity of 1,1,1,3,3-pentafluoropropane ( HFC-245fa) was measured in both the saturated liquid and the vapor phase by the transient double hot-wire method. Measurements of the thermal conductivity of the saturated liquid HFC-245fa were reported over the temperature range from ( 243 to 413) K while in vapor phase were from ( 293 to 413) K along 13 quasi-isotherms and at pressures up to saturation. The total uncertainly of the experiment was less than +/- 2.0 %. The results of liquid phase were correlated as a function of temperature as well as the gas-phase results were correlated as a function of temperature and pressure. The standard and maximum deviations of the liquid experimental results from the correlation were less than 0.21 % and - 0.56 %, respectively. The maximum deviation and the absolute mean deviation of the gaseous measured data from its equation were 0.87 % and 0.38 %, respectively.