Areas of solid surfaces as small as 0.1 cm2 were determined by xenon adsorption at liquid oxygen temperature using an adsorption apparatus with a temperature-compensated, differential tensimeter of symmetrical design. The thermal transpiration effect was considered to determine the adsorption pressures and the amount adsorbed. The Brunauer–Emmett–Teller monolayer volume of xenon for 4, 8, or 12 1 mm steel ball bearings was proportional to the number of balls used. The coefficient of proportionality agreed with the results on 9880 ball bearings. The surface area of four ball bearings is 0.12 cm2, which suggests that it is feasible to measure surface areas as small as 0.1 cm2. © 1997 American Institute of Physics.