Synthesis, crystal structure, vibrational and dielectric properties of [C7H18N2]2ClBiCl6.H2O are reported. The compound crystallizes at room temperature in the orthorhombic system, space group P212121, with the following unit cell parameters : a = 7.5500(6) Å, b = 18.3780(2) Å, c = 19.8980(13) Å, V = 2760.9(4) Å3 and four molecules per unit cell. The structure has been solved by three-dimensional Patterson synthesis and refined by least-squares analysis (R1 = 0.0463, wR2 = 0.0764). The crystal structure of the title compound, [C7H18N2]2ClBiCl6.H2O consists of 2-(2-Aminoethyl)-1-methylpyrrolidinium cations, [BiCl6]3- anions, Cl- anions and free water molecules. The Bi(III) cation is coordinated by six Cl- anions in slightly distorsed octahedral geometry. In the crystal, extensive intermolecular N-H…Cl hydrogen bonds occur. The charge-transfer (CT) interactions between 2-(2-Aminoethyl)-1-methylpyrrolidinium cation and the anionic hosts have been revealed by structural analysis and UV-vis spectroscopy. The dielectric properties have been investigated at temperature range from 100 to 300 K at various frequencies (1 KHz – 1 MHz). The evolution of dielectric constant as a function of temperature and frequency of pellet has been investigated in order to determine some related parameters.