A pressure swing adsorption apparatus for the removal of one or more components such as oxygen from a mixture of gases such as air is disclosed. The apparatus includes pairs of columns (14, 16) for receiving a stream of compressed air with one column operating in a working mode whilst the other said column operates in a purging mode. The columns contain carbon molecular sieve material (26) for adsorbing oxygen and a desiccant material formed into a plurality of tubes (28).