The doping limit of carbon in GaAs grown by organometallic vapor phase epitaxy (OMVPE) using carbon tetrachloride (CCl4) as a p‐type dopant source has been investigated by variation of the V/III ratio, growth temperature, and CCl4 flow rate. Lower V/III ratios, lower growth temperatures, and higher CCl4 flow rates generally yielded higher hole concentrations. Hole concentrations as high as 1020 cm-3 were achieved. Attempts to achieve higher hole concentrations via higher CCl4 flow rates were limited by inhibition of growth and morphology degradation. Majority‐carrier hole mobilities of carbon‐doped GaAs were more than 50% greater than that of zinc‐doped GaAs for comparable hole concentrations obtained in previous work. Nonalloyed contacts to this material resulted in contact resistivities of 4×10-7 Ω cm2.