Experiments on skin moisture, i.e. the hydration state of the outer epidermis, were undertaken using three different types of equipment, i.e. the Skicon-100 and Corneometer CM 420 hydrometers and the Servo Med EPI evaporimeter. The studies included 10 healthy volunteers. Water was applied to test sites on the forearm and the palm of the hand, and effects monitored by the three methods. Parallel increases in conductance, capacitance and transepidermal water loss were registered for a duration of about 5 min. The Skicon-100 was more sensitive for measurement of increased hydration, while the Corneometer CM 420 might be more sensitive for measurement of decreased hydration. Inter- and intra-individual variations were minor with all instruments. According to reproducibility studies, the Corneometer CM 420 was more accurate than the Skicon-100. Technical experiments indicated that the Corneometer CM 420 depicts changes of hydration down to a depth of 0.1 mm, while the Skicon-100 measures very superficially. In conclusion, both hydrometers were deemed relevant and valid for assessment of skin moisture. The methods are complementary, and their combined use is recommended.