The MOVPE growth of GaAs in a hot-wall system has been investigated using diethylgallium chloride ((C2H5)2GaCl, DEGaCl), AsH3 and H2. Recent measurements have determined the vapor pressure of DEGaCl, and have also determined that DEGaCl is dominantly associated as multimers in the gas phase. The growth temperature range of 350 ≤T≤ 700°C was investigated at reactor pressures of 0.10-10 Torr. The substrates were mounted parallel to the average gas flow direction throughout the study. The very low temperature at which the growth rate is reaction rate-limited in the hot-wall reactor may be attributed to the conversion of DEGaCl to a species that is more readily incorporated as GaAs, such as GaCl. At higher temperatures, the growth rate typically demonstrates a monotonic decrease with downstream location that may result from both the depletion of GaCl in the reactor, and/or a lower supersaturation of GaCl in the gas phase due to increasing concentrations of HCl down the length of the reactor. At even higher temperatures a drastic drop in growth rate may also be caused by the depletion of GaCl and/or the lower supersaturation of GaCl in the gas phase. The carrier concentration in the grown material is below 2.5x1014 cm-3 at 450°C and increases at higher temperatures to 5x1015 cm-3 n-type at 650°C. © 1991.