AlGaN with the Al content in the range of 10-30% is one of the key materials for production of the optoelectronic devices operating in the UV spectral range. At the same time there are well-known difficulties in growing such layers by MOVPE, associated with low efficiency of aluminum incorporation in AlGaN, caused by parasitic gas-phase reactions. In this paper, the results of a combined experimental and modeling study of AlGaN growth in a production scale multiwafer (6 x 2") AIX2000HT Planetary Reactor are reported. The effects of reactor pressure, total flow rate and metalorganic flow rate variations on aluminum incorporation have been Studied experimentally. Detailed simulations of flow dynamics and chemistry have enabled to identify the mechanisms responsible for aluminum losses in the gas phase. Model predictions have been found in good agreement with the experimental data in a wide range of growth conditions and AlGaN compositions. From the results obtained, possible strategies of growing high-Al content AlGaN are proposed. (C) 2004 Elsevier B.V. All rights reserved.