In this work, nanocrystals of LTA zeolite with crystallite sizes ranging from 30 to 70 nm were synthesized successfully. Tetramethylammonium hydroxide (TMAOH) was used as template. The effects of organic and inorganic cations as well as crystallization conditions including aging time, synthesis time, and synthesis temperature on size of the zeolites were studied. The crystallite size was adjusted by varying the compositions of synthesis gel and also crystallization conditions. The final products were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The obtained results showed that zeolite size decreases significantly and zeolite size distribution becomes narrow by increasing aging time, and organic cation content. Moreover, the zeolite crystallite size increases significantly by increasing inorganic cation content. It was found that reaction time has a great effect on crystallinity of the synthesized zeolites. It was indicated that nucleation is completed after 3 days and no further nucleation occurs after. (C) 2012 Elsevier B.V. All rights reserved.