Subjects for the invention are to provide a zeolite reduced in performance deterioration in repetitions of use or during long-term use and a process for producing the same and to provide an adsorbent comprising the zeolite and a heat utilization system or the like employing the adsorbent.The invention relates to a zeolite which has a framework density of from 10 T/nm.sup.3 to 16 T/nm.sup.3 and a carbon content of from 1% by weight to 6% by weight and satisfies the following (1) or (2): (1) the zeolite is an aluminophosphate which has a nitrogen content of from 0.5% by weight to 12% by weight and in which the aluminum may be partly replaced by Me; (2) the zeolite is a silicoaluminophosphate in which the aluminum may be partly replaced by Me and which, when burned to a carbon content lower than 0.3% by weight, retains the framework structure possessed by the silicoaluminophosphate before the burning: (provided that Me in (1) and (2) above is at least one element selected from the elements in Groups 2A, 7A, 8, 1B, and 2B of the periodic table).