alpha-Fe2O3 thin films were deposited on Al2O3 substrate by PECVD process Fe(CO)(5) was used as a source material and was introduced into the reactor using Ar-O-2 as the transporting gas. Characterization of as-deposited alpha-Fe2O3 thin film was tried in terms of the effects of the deposition variables such as substrate temperature. RF plasma generating power, post annealing treatment and the flow rate of O-2 and Ar. As deposited alpha-Fe2O3 phase was: relatively more stable in the temperature range from 80-100 degrees C. Fe3O4 phase was observed above 120 degrees C. On the basis of BET measurements and AFM observations, it became clear that the film deposited on the non-polished substrate has more specific surface area, which is strongly related with gas sensing mechanism, than that on the polished substrate. For the future sensor application, the porous structure of alpha-Fe2O3 was successfully fabricated on the non-polished Al2O3 substrate in the temperature range from 80-100 degrees C by 100 W of RF power.