Large colorless single crystals of analcime with diameters up to 0.20 mm have been synthesized from gels with the composition of 3.00SiO ₂ : 1.50NaAlO ₂ : 8.02NaOH : 454H ₂ O : 5.00TEA. The fully Na ⁺ -exchanged analcime have been prepared with aqueous 0.1 M NaCl (pH adjusted from 6 to 11 by dropwise addition of NaOH). The single-crystal structure of hydrated |Na _0.94 (H ₂ O)|[Si _2.06 Al _0.94 O ₆ ]-ANA per unit cell, a =13.703(3) Å, has been determined by single-crystal X-ray diffraction technique in the orthorhombic space group Ibca at 294 K. The structure was refined using all intenties to the final error indices (using only the 1,446 reflections for which F_o > 4σ( F_o )) R ₁ / wR ₂ =0.054/0.143. About 15 Na ⁺ ions are located at three nonequivalent positions and octahedrally coordinated. The chemical composition is Na _0.94 (H ₂ O)Si _2.06 Al _0.94 O ₆ . The Si/Al ratio of synthetic analcime is 2.19 determined by the occupations of cations, 14.79, in the single-crystal determination work.