AbstractThe heat uptake that resulted from immersing the hand and wrist into a water‐filled calorimeter maintained at temperatures between 37–40 °C was measured under standard conditions in a group of eight subjects of either sex. The rate of heat transfer (W) increased exponentially with temperature and was a function of hand or body size and age, but not sex. The heat transfer rate normalized to hand mass (W.kg−1) was determined by temperature and age: best‐fit mean values (and 95% confidence limits of the population) were 6.0 W.kg−1(3.2–11.2 W.kg−1) at an immersion temperature of 37 °C and 25.4 W.kg−1(13.7–47.0 W.kg−1) at 40 °C. The application of these results to limits on specific energy absorption rate induced in the hands and wrists by radiofrequency dielectric heat seale