The new organic– inorganic hybrid 1,7-heptanediammonium-calcium tetrachloride, with molecular formula [(CH2)7(NH3)2] CaCl4, crystallized in a monoclinic Pm space group, a= 4.625 A˚ , b = 11.205 A˚ , c = 12.391 A˚ ,  = 900  = 86.82 0,  = 900, V = 641.2 A˚3, density= 1.63 mgm-3 and Z= 2. Differential thermal scanning of the new organic–inorganic hybrid showed five phase changes; chain melting transitions at T1= 329.2 K and T2 = 326.49 K and three transitions at T3= 283.6 K, T4= 278.8 K and T5= 260.8 K associated with solid– solid phase changes. Permittivity and ac conductivity as a function of temperature (170 K- 425 K) and frequency (0.06 kHz