Some of the thermal and optical properties of skin have been determined for sources and exposure conditions involved in the study of the effects of intense radiation on uncovered and subfabric skin. The surface temperatures of irradiated painted and unpainted skin were measured with fine-wire thermocouples for exposure times ranging from 0.1 to 20 seconds, at radiation levels lower than those which would cause pain in the subject. The value of the important thermal parameter, the kρc product (k, thermal conductivity; , density; c, specific heat), as determined from the measured surface temperatures of blackened skin was found to be 8.6 x 10−4 centimeter-gram-second units. The surface temperatures of skin when exposed to carbon-arc, to 3000°K tungsten, and to infrared radiation are approximately one-half those of blackened skin, and 30% less than those computed from opaque-solid theory. Good agreement between heat-flow theory and experiment on human skin is obtained if it is assumed that the skin is a homogeneous diathermous solid with a diathermancy which varies with wavelength. Submitted on January 18, 1957