Pseudomorphic high electron mobility heterostructures are demonstrated by atmospheric pressure metalorganic chemical vapor deposition for the first time. Transmission electron microscopy (TEM), variable temperature Hall effect measurements, Shubnikov–de Haas measurements, and photoreflectance were applied to characterize the heterostructures. TEM micrographs of the cross section reveal sharp heterojunction interfaces. Variable temperature Hall effect measurements show a monotonic increase in mobility as the temperature is lowered. With a spacer thickness of 120 A˚, a peak mobility of 80 000 cm2/V s at 20 K and a sheet carrier concentration of 1.05×1012cm−2are obtained. Similarly, a thinner spacer (60 A˚) shows a peak mobility of 57 000 cm2/V s at 25 K with a sheet carrier concentration of 1.40×1012cm−2. Shubnikov–de Haas measurements in magnetic fields up to 18.5 T show clear oscillations and the quantum Hall effect confirming the existence of a two‐dimensional electron gas.