The first measurement of impedance on free-standing diamond films from 0.1 Hz to 10 MHz up to 300°C werereported. A wide range of chemical vapour deposition (CVD) materials were investigated, but here we concentrateon ’black’ diamond grown by microwave plasma enhanced CVD (MWPECVD). The Cole-Cole (Z’ via Z“) plotsare well fitted to a RC parallel circuit model and the equivalent resistance and capacitance for the diamond filmshave been estimated using the Zview curve fitting. The results show only one single semicircle response at eachtemperature measured. It was found that the resistance decreases from 62 MΩ at room temperature to 4 kΩ at300°C, with an activation energy around 0.51 eV. The equivalent capacitance is maintained at the level of 100 pF upto 300°C suggesting that the diamond grain boundaries are dominating the conduction. At 400°C, the impedance atlow frequencies shows a linear tail, which can be explained that the AC polarization of diamond/Au interface occurs. The first measurement of impedance on free-standing diamond films from 0.1 Hz to 10 MHz up to 300 ° C were reproduced. A wide range of chemical vapor deposition (CVD) materials were investigated, but here we concentrateon ’black’ diamond grown by microwave plasma enhanced CVD (MWPECVD). The Cole-Cole (Z ’via Z ”) plots well well to a RC parallel circuit model and the equivalent resistance and capacitance for the diamond films have been estimated using the Zview curve fitting. The results show only one It was found that the resistance decreases from 62 MΩ at room temperature to 4 kΩ at 300 ° C with an activation energy around 0.51 eV. The equivalent capacitance is maintained at the level of 100 pF up to 300 ° C suggests that the diamond grain boundaries are dominating the conduction. At 400 ° C, the impedance at low frequencies shows a linear tail, which can be explained that the AC polarization of diamond / Au interface occurs.