Praseodymium (Pr) emissions were investigated for Pr‐implanted GaAs and AlxGa1−xAs as a function of Al mole fraction, sample temperature, and anneal temperature using photoluminescence (PL) spectroscopy. Two groups of major PL peaks have been observed near 1.6 and 1.3 &mgr;m, which can be attributed to the crystal‐field‐split spin‐orbit level transitions of3F3→3H4and1G4→3H5of Pr3+(4f2), respectively. The PL intensity of Pr3+varies dramatically with the Al mole fraction in Pr‐implanted AlxGa1−xAs. For GaAs, the PL peak intensity near 1.3 &mgr;m is strong and the peak intensity near 1.6 &mgr;m is weak, whereas the PL peak intensity near 1.6 &mgr;m is much stronger than that of 1.3 &mgr;m for AlxGa1−xAs. Furthermore, Al0.15Ga0.85As shows particularly strong luminescence peaks near 1.6 &mgr;m. PL emissions of Pr were detected for sample temperatures as high as 100 K, and several hot lines were identified. The optimal anneal temperatures for the Pr‐implanted GaAs and AlxGa1−xAs are between 725 and 775 °C. Dual implantations of Pr and Er into Al0.15Ga0.85As have also been made, but the PL results showed that the emission intensities of both ions did not increase compared to those of identically prepared singly implanted samples. Possible excitation processes are explored in light of these results.