The shape of the sweetness function remained unaltered when different concentration ranges of sucrose were evaluated at different temperatures by either one of two psychophysical methods: magnitude estimation or magnitude matching. Results of the sweetness-temperature interaction showed that cool solutions were judged less sweet than warmer solutions. Furthermore the rate of growth of sweetness increased with decreasing temperature, but this effect disappeared when the concentration reached between 0.4 and 0.5 M. That point coincides with the zone in which sweetness functions typically show an inflection point. When Beidler's taste equation was applied to psychophysical data obtained at constant or variable temperature, it was possible to show that sweetness is mediated by an adsorption process rather than an enzymatic reaction.