The dielectric relaxation behavior of hydroxyl-terminated poly tetrahydrofuran (HO-PTHF-OH) network has been investigated.The networks were prepared by a hydrolysis condensation process of the 3-isocyanato propyltriethoxysilane end capped-oligmers for the crystalline relaxation covering a range in the temperature and frequency. Also, the crystallization process of the investigated sample has been studied dielectrically as a function of time and temperature. Furthermore, the results obtained showed that (i) the optimum crystallization tem- perature is about 25 0C; (ii) the time at which crystallization starts is a function of the working temperatures and apparently isreduced to just a few minutes at 30 0C; and (iii) the crystallization processis completed within a period of less than 1 hrs in the temperature range 20-30 0C.