Abstract MOCVD grown Al x Ga 1− x As epitaxial layers with x=0.45 and GaAs single crystals with an initial dislocation density less than 10 3/cm 2 were implanted with different doses of 1.5 MeV Se + and 1.0 MeV Si + ions and 170 keV protons at room (RT) and liquid nitrogen temperatures (LNT). In all cases the ion range was close to 1 μm. The samples were studied with a number of complementary X-ray methods, most of them with synchrotron radiation. The synchrotron methods revealed many interference phenomena which were used for the strain profile analysis based on fitting the simulated rocking curves and Bragg-case section topographs. It was found that the amorphisation of Al 0.45Ga 0.55As took place only after implantation at LNT. Upon implantation at RT an increase of the lattice parameter was observed that eventually saturated with an increasing ion dose. Also the flattening of the strain profile close to the surface was observed. Most of the observed strain effects were attributed to the point defects in the matrix crystal. For the highest doses the second strain component corresponding to the distribution of introduced ions was revealed.