Abstract: The specification describes a portable temperature sensing device adapted to maximize heat transfer from a selected location on a planar surface to the device while minimizing heat transfer from surrounding conditions. The device includes a frame made of thermal insulating material provided with a sealed cavity, a temperature measuring instrument in the sealed cavity, a heat transfer member having a high thermal conductivity and extending from the cavity to the exterior surface of the frame for intimate contact with the planar surface, and means for reading the temperature measuring instrument. The arrangement is such that the heat transfer member is essentially isolated from thermal effects of surrounding conditions when the device is in use.