¹H MAS NMR spectra of Bi_0.05Eu_0.05Y_0.90PO₄·𝑥H₂O show chemical shift from −0.56 ppm at 300 K to −3.8 ppm at 215 K and another one at 5–6 ppm, which are related to the confined or interstitial water in the hexagonal structure and water molecules on the surface of the particles, respectively. Negative value of the chemical shift indicates that H of H₂O is closer to metal ions (Y³⁺ or Eu³⁺), which is a source of luminescence quencher. H coupling and decoupling ³¹P MAS NMR spectra at 300 and 250 K show the same chemical shift (−0.4 ppm) indicating that there is no direct bond between P and H. It is concluded that the confined water is not frozen even at 215 K because of the less number of H-bonding.