Galvanic skin conductance (GSC) increases prior to sweat reaching the skin surface [1], indicating\npre-secretory sweat gland activity. Sweat travels through the duct and penetrates the stratum\ncorneum (SC) causing epidermal hydration (HYD). Boucsein [2] claimed that SC hydrates first\nbefore sweat is released onto the skin surface. GSC is influenced by sweat within the glands, HYD\nand sweat on the skin surface [3]. The aim of this experiment is to determine the extent to which\nthese contribute to the value of GSC.