An improved method of making binderless zeolite sieve extrudates. After extruding a mixture containing about 40-60% zeolites with the remainder being a metakaolin clay that has mixed with it about 90-120% of the stoichiometric amount of sodium hydroxide to convert the clay to a zeolite, the extruded particles are allowed to dry age under dry, bulk conditions in a container during which time autogeneous heat develops and most of the clay is converted to the zeolite. A further heat treatment in a dilute caustic aqueous solution may be used to insure complete crystallization with subsequent washing and calcination to produce an adsorbent product.