Time‐resolved photoluminescence (PL) spectroscopy has been performed on erbium‐doped Ga0.55Al0.45As. We have investigated the4I13/2→4I15/2optical transition. The measured fluorescence lifetime is around 1.2 ms which is similar to values found for other erbium‐doped III‐V compounds. Studies as a function of temperature indicate nonradiative transitions characterized by thermal activation of 40 meV. With the help of two beam experiments we have confirmed the existence of Auger losses during the PL excitation and a model of the excitation process is proposed that accounts for the experimental results.