TPD (also known as TDS) involves heating a sample while contained in a vacuum and simultaneously detecting the residual gas in the vacuum by means of a mass analyser. As the temperature rises, certain absorbed species will have enough energy to escape and will be detected as a rise in pressure for a certain mass.

There are two approaches to this thermal evaporation technique:

(a) Raise the temperature of the sample very quickly (about 1/2 a second is typical). This is known as flash desorption.

(b) Slowly raise the temperature of the sample (between 15 seconds to several minutes). This technique is known as temperature programmed desorption. As the temperature rises and a particular species is able to desorb from the surface, the pressure will rise. As the temperature rises still further the amount of the species on the surface will reduce causing the pressure to drop again. This results in a peak in the pressure versus time plot.

The temperature of the peak maximum provides information on the binding energy of the bound species.

TPRS is a related technique where reactions on the surface may occur as the temperature rises.