Data on thermal conductivity of liquids, as a function of temperature, are essential in the design of heat- and mass-transfer equipment. A number of correlations have been developed to predict thermal conductivity of liquids with limited success. Among the correlations proposed so far, only the correlation due to Nagvekar and Daubert (Ind. Eng. Chem. Res. 1987, 26, 1362) is based on group contributions. In this paper, a new group contribution method is developed based on the Klaas and Viswanath (Ind. Eng. Chem. Res. 1998, 37, 2064) method for prediction of thermal conductivity of liquids and the results are compared to the method of Nagvekar and Daubert and other existing correlations. The present method predicts thermal conductivity of some 228 liquids that encompass 1487 experimental data points with an average absolute deviation of 2.5%. The group contribution method is used to examine the temperature dependence of Prandtl number for vegetable oils.