In this paper, a-particle detectors have been fabricated using good quality polycrystalline CVD diamond thin films deposited by HFCVD technique. Coplanar electrical contacts with interelectrode spacing of 100 mum were prepared on the growth side of the CVD diamond film using lift-off technology. The detector performance has been tested with a Am-241 source with a characteristic energy of 5.5 MeV at room temperature. The experimental results show that the charge collection efficiency of the fabricated CVD diamond-based alpha-particle detector in the normal state reaches 32%. (C) 2002 Elsevier Science Ltd. All rights reserved.