Lattice dynamics and bond characteristics in SnCl4. 5H(2)O have been investigated using Cl-35 nuclear quadrupole resonance (NQR). Two chemically inequivalent chlorine sites in SnCl4. 5H(2)O were distinguished from the temperature dependences of the NQR frequency and from the spin-lattice (T-1Q) and spin-spin relaxation times (T-2Q) The anomalous temperature dependence of the NQR frequency of one of the two sites was attributed to a thermal weakening of the crystal held from uncoordinated water molecules. In addition, high temperature activated molecular motion was observed.