The use of Al(2)O(3) dielectric in MOS based radiation sensors has been investigated. Their response has been compared with conventional MOS capacitors with a SiO(2) dielectric. The study includes gamma radiation effects with dose up to 4 Gy. The effect of radiation has been determined from the valance band shift in CV curves. The amount of charge induced by the radiation has been calculated and compared with the response of MOS capacitors with SiO(2) with the same and different thicknesses. Fading properties have been studied and compared. Results show that MOS capacitors with Al(2)O(3) dielectric exhibit sensitivity greater than that obtained from MOS capacitors with SiO(2). This higher sensitivity is attributed to higher trapping efficiency in the Al(2)O(3) layer. (C) 2008 Elsevier B.V. All rights reserved.