Photoluminescence spectroscopy has been used to investigate the behavior of Hg, implanted into MBE‐grown GaAs. A new recombination path in the near‐band‐edge region at 1.51291 eV is identified with the neutral Hg‐bound exciton recombination (Hg°X), with a localization energy following an anti‐Haynes’ rule. The electron‐acceptor and donor‐acceptor transitions are displayed at 1.466 and 1.463 eV, respectively. From the temperature dependence of the photoluminescence, the value of 52.5 meV is extracted for the binding energy of the Hg acceptor in GaAs. With the resonant excitation of the Hg°X line, the electronic signature of the Hg acceptor in GaAs is further evidenced, with the observation of two‐hole transitions. Transitions to 2s as well as 3s states are resolved, with Raman shifts of 37.2 and 44.8 meV, respectively. The corresponding binding energies are thus 15.3 and 7.7 meV, respectively. © 1995 American Institute of Physics.