Display omitted •The cooling rate dependence of the glass transition is measured in a cooling rate range of more than six decades.•The cooling rate dependence of the glass transition can be described by a Vogel–Fulcher–Tammann–Hesse equation.•The influence of the heat transfer conditions in a Flash DSC is discussed. The thermal glass transition of polystyrene (PS) is measured in a range between 0.003K/s and 4000K/s using a conventional DSC 1 and a Flash DSC 1 from Mettler-Toledo. The dependency between the cooling rate and the glass transition temperature is in accordance with the Vogel–Fulcher–Tammann–Hesse (VFTH) equation, as it is usually used for description of the frequency–temperature relationship of the dynamic glass transition (or main relaxation process). Furthermore we discuss the influence of the thermal lag on the measurement and develop correction methods.