Power-compensated differential scanning calorimeters are often used in measurements on cooling, In this paper we discuss and present new results on different methods for calibration for cooling, Liquid-crystals have transitions characterized by very little supercooling and are here used for calibration purposes. A difficulty is that the transitions of liquid-crystals usually occur in a narrow temperature range. The temperature range of precise calibration is evaluated for some metals by a method based on reversing the heat flow immediately after the beginning of melting. Further, we investigate the crystalline-plastic-liquid transitions of some alkanes. Finally, we calculate temperature profiles inside two samples of different thermal diffusivity. The results highlight important differences in the temperature distributions in organic and metallic substances under different conditions.