An experimental investigation on the thermal decomposition of CH(4) into C and H(2) was carried out using a 5 kW particle-flow solar chemical reactor tested in a solar furnace in the 1300-1600 K range. The reactor features a continuous flow of CH(4) laden with mu m-sized carbon black particles, confined to a cavity receiver and directly exposed to concentrated solar irradiation of up to 1720 suns. The reactor performance was examined for varying operational parameters, namely the solar power input, seed particle volume fraction, gas volume flow rate, and CH(4) molar concentration. Methane conversion and hydrogen yield exceeding 95% were obtained at residence times of less than 2.0 s. A solar-to-chemical energy conversion efficiency of 16% was experimentally reached, and a maximum value of 31% was numerically predicted for a pure methane flow. SEM images revealed the formation filamentous agglomerations on the surface of the seed particles, reducing their active specific surface area. (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.