Five Sample of Ni2+ exchange X-zeolites were prepared by ion exchange technique and were studied by chemical analysis, thermogravimetric analysis (TGA) and differential thermal analysis (DTA) to determine their unit cell composition, Zeolite water and thermal stability. The percentage of cation exchange decreased with increasing the concentration of Ni2+ cations in the exchange solution. The water contents of the zeolite X increased with increasing the Ni2+ contents per u.c of the zeolite. The dehydration Na X completed at 380oC and those of Ni X-zeolite samples at 420-470oC and the total weight loss occurred at 800oC for Na X and Ni X zeolites at 900-980oC depending on the Ni2+ cation loading of the zeolite. The thermograms were of lumpy nature indicated formation of a series of intermediate structure during dehydration. The endothermic peak of dehydration shifted towards high temperature for Ni X-zeolites indicated H2O molecules are more strongly bonded to Ni2+ cations than Na+ cation. The positions of exothermic peaks indicated that Calcined NI X-zeolites samples are thermally less stable than Na X-zeolite. The DTA curves indicated that Na X-zeolite becomes amorphous at above 930oC and NI X-zeolites at 800-870oC. the above results are discussed and possible interpretations are given.