In this work, thermal conductivities of a homologous series of liquids n-pentane, isopentane, 1-pentene, and 1-pentanol were measured from 253 to 373 K at pressures up to 30 MPa with a transient hot-wire apparatus. The relative expanded uncertainty of the reported data was estimated to be 2.0% with a confidence level of 0.95 (k = 2). The polynomial thermal conductivity model was used to correlate the experimental values for each of the fluids. The average absolute percentage deviations of the experimental results from fitting were 0.3, 0.3, 0.3, and 0.1%. Comparisons were provided between the data obtained in this work and published literature.