GaInAs grown on InP at atmospheric pressure using organometallic vapor phase epitaxy is characterized by x‐ray diffraction, transmission electron microscopy (TEM), and Hall measurements. The sources used are TMIn, TMGa, AsH3, and PH3 in a carrier gas of H2. Double crystal x‐ray diffraction is used to evaluate the mismatch and crystal quality of the GaInAs epitaxial films. Full widths at half‐maximum intensity (ω1/2) of the double crystal diffraction peak as small as 50 arc s are obtained. The average ω1/2 is less than 80 arc s for all films grown at deposition temperatures between 520 and 540 °C and with mismatch strains between −4×10−3 and +1×10−3. Standard TEM is used to image Ga0.47In0.53As on InP in cross section. No planar defects and few dislocations are present. High resolution TEM of the Ga0.47Ino.53As/InP interface shows that no strain or mismatch related defects are present for nearly lattice‐matched films. Hall mobilities of 10 500 and 47 500 cm2/Vs at 300 and 77 K are measured at n=2×1015 cm−3. These values are comparable to those of good liquid phase epitaxial layers.