We reported the growth and its electrical properties of [100]-oriented diamond film using alcohol and hydrogen by HFCVD. SEM and Raman measurements indicated that high quality polycrystalline diamond films with [100]-faced structure were obtained. Dark current-voltage (I V), capacitance-frequency (C F), capacitance-voltage (C-V) and photocurrent under steady-state 55 Fe 5.9 keV X-ray excitation of freestanding diamond film were investigated at room temperature. Results indicated that after post-annealing for [10 0]-oriented diamond films dark current was in the order of 10(-10) A and the photocurrent was of in the order 10(-8) A by X-ray irradiation with the applied voltage of 40 V, capacitance and dielectric loss were very small with the value of 2 pF and 2 x 10(-3) with the bias voltage of 0.05 V, respectively, and almost had no variation with the change of frequency in high frequencies from 100 kHz to 10 MHz. (c) 2005 Elsevier Ltd. All rights reserved.