Measurements of the thermal conductivity of HFC-134a made in a coaxial cylinder cell operating in steady state are reported. Measurements were performed along several quasi-isotherms at temperatures ranging from the critical temperature T(c) (similar to 374 K) to T(c) + 150 K and in a pressure range from (0.1 to 40) MPa. Parameters of a background equation were determined from experimental data to analyze the critical enhancement of the thermal conductivity as a function of temperature and density. An analysis of the various sources of errors leads to an estimated uncertainty of the thermal conductivity data of +/- 3%.