Clinoptiloite transforms to analcime under hydrothermal condition in presence of alkaline fluids. The effect of Na+ and K+ concentrations, temperature and run duration are being considered as the variable parameters in the present study. Alkaline solutions were used in concentration of 1.25 up to 7.5mol/lit under temperatures of 100 and 150 ?C. Results of this study show that analcime is synthesized at 150?C and high concentration of Na+. With increasing Na+ content of the fluids and reaction time, the amount of analcime increases drastically. Powder X-ray diffraction study has revealed an orthorhombic symmetry with the unit-cell parameter of a: 13.731 ?, b: 13.726 ?, c: 13.769 ?.