One of the fundamental properties of any adsorbent is surface area. The most common way of determining the surface area of is application of the BET (Brunauer, Emmet, and Teller) model to nitrogen isotherm data in the appropriate pressure ranges, at liquid nitrogen temperatures. The resulting BET surface area can be determined by a multi-point isotherm or estimated using a single point measurement. Using standard methods surface areas ranging from 5 m2/g to 2000 m2/g can easily be determined for a variety of porous materials.