Abstract: An apparatus for measuring thermal discomfort originating from an asymmetry in a thermal field comprises two blackened surfaces facing in opposite directions and maintained at a common temperature higher than that of the surrounding air. The difference in power required to maintain the same higher temperature of the two surfaces is measured and is an expression of the thermal discomfort. If the thermal influence varies with time the probe may have the same thermodynamic characteristics as the human skin or these characteristics can also be obtained by an electric filter.