The relative merits of sorption pumps and rotary oil pumps are compared. Despite their use being limited to ‘closed’ systems of small volume and the need for liquid nitrogen cooling, the advantages of sorption pumps, especially their freedom from contamination, lack of noise and vibration, and ability safely to handle toxic vapours are felt to make them suitable for wider applications in laboratory situations. Two types of sorption pump, fitted with effective venting valves (which are essential for safe operation) and designed for rapid pumping, are discussed in some detail. Results are presented for rate of pumping as a function of system size, type of molecular sieve used, storage time, sieve regeneration temperature, time of prechilling and pump configuration. A variety of physico-chemical applications for sorption pumps are discussed, including their use as the sole means of evacuating small quadrupole mass spectrometers. It is recommended that a ratio of 50 g of type 13X, 1/8 in. molecular sieve pellets to 1 dm3 of system volume be used. The sieve should be regenerated every 5 cycles for clean systems and every cycle for dirty systems, at a temperature of 250°C. The sieve can be stored for long periods in screw topped bottles. Prechilling is not recommended.