Thermal conductivities of n-octane, isooctane, 1-octene, and 1-octanol were measured with a transient hot-wire apparatus. The measurements for these fluids covered a temperature range from 253 to 373 K with pressures up to 30 MPa, except for 1-octanol which covered a temperature range from 273 to 393 K. The relative expanded uncertainty with a level of confidence of 0.95 (k = 2) of the data was estimated to be better than 2.0%. The experimental values were correlated by a polynomial thermal conductivity model for each of the fluids. The average absolute percentage deviations were all within 0.3%. Comparisons between the data obtained by this work and published literature studies are also presented here.