Small carbon particles have excellent absorption properties for concentrated solar radiation. Oxidation rates of micron and submicron sized carbon black particles have been investigated under high flux solar conditions. These oxidation rates are required for a thermal model of direct absorbing particle receivers as well as for the development of solar chemical technologies to treat toxic wastes. An experimental set-up has been developed for kinetic measurements in the solar furnace of the DLR. In the temperature range 600-900 degrees C no significant acceleration of the oxidation could be observed due to insolation up to irradiances I less than or equal to 700 kW m(-2) as compared to thermal oxidation of carbon particles (Derussol C(C)).