Polycarbonate (PC) is a popular polymer material used among other things, for electric tool casings. To optimize the production/molding process by finite element simulations, the thermophysical properties have to be known. The thermal diffusivity can be determined not only in the solid region but also at temperatures above the glass transition (> 140°C) if a molten material cell is employed in the LFA 457 MicroFlash®. Together with the specific heat (measured with a DSC) and density data, the thermal conductivity can be determined. The slight increase in the thermal conductivity versus temperature is typical for 100% amorphous materials. Furthermore, the glass transition is visible in the specific heat curve and in the thermal diffusivity result. In the thermal conductivity result, this second order transition cannot be seen.