ABSTRACT The thermal conductivity of four amorphous polymers was determined within a wide range of temperatures, starting at room temperature up to above the glass transition temperature (Tg). In this work, the hot wire technique was adopted for the experimental measurements and the thermal conductivity was directly determined in the temperature interval analyzed. As expected, the experimental results show that Tg exerts a measureable influence on the thermal conductivity of amorphous polymers. For such materials, the dependence of the thermal conductivity with the temperature is quite different from that foreseen by dieletric materials. The thermal conductivity behaviour with temperature displays two distinct regions: in the glassy state before Tg and in the rubbery state after Tg. The influence of this transition temperature on the thermal conductivity behaviour with temperature has been analysed in terms of phonons conduction process, specific heat variations with temperature and modulus of elasticity of the analyzed polymers, in order to explain this apparently anomalous behaviour. This effect is hardly detectable for semi-crystalline polymers, since only the amorphous phase is responsible for this behaviour, and the crystalline phase overrides this influence. Keywords: Thermal transition temperatures, thermal conductivity, phonons heat conduction, hot wire technique. *Corresponding author.