In this first report in a series of studies to measure the thermal conductivity of fluids at high temperature and high pressure, preliminary studies on the reliability of a transient hot-wire method and measured results of eight liquids are described. Measurements were performed for water, methanol, ethanol, benzene, acetone, glycerin, refrigerants R11 and R113 at atmospheric pressure in the temperature range -90 - +80°C. Empirical correlations were established for each liquid. Comparisons with available data in literatures showed reasonably good agreement for most of liquids.