Locations of water molecules and exchangeable cations in a hydrated natural chabazite with a composition of Ca_1.57Na_0.49 [Al_3.39Si_8.55O₂₄] ⋅12.47H [d2] O were successfully determined by single crystal X-ray diffraction. The structure analyses have revealed the presences of five partially occupied water sites (OW1-OW5) and four partially occupied exchangeable-cation sites (Ca1-Ca4), and have showed that fully coordinated exchangeable cations can adopt sixfold or sevenfold coordination. The distances between water sites and framework oxygen sites and between water sites suggest that the hydrogen bonds formed between water molecules and framework oxygen atoms are very weak, whereas strong hydrogen bonds exist between water molecules.