Photoluminescence (PL) for GaAs immersed in hydrochloric acid (HCl 36% aqueous solution, hereafter denoted as HCl aq.) diluted with organic solvents was studied. The PL intensities from GaAs immersed in solutions of HCl aq.-methanol and HCl aq.-trichloroethane were stable and stronger than that of GaAs in air. The PL intensities frnm GaAs immersed in HCl aq.-ethanol, HCl aq.-isopropyl alcohol, HCl aq.-acetone, and HCl diluted with water were weak as compared to that of GaAs immersed in HCl aq.-methanol. Strong PL intensity of GaAs immersed in HCl aq.-methanol solution is considered to be attributed to prevention of arsenic segregation and oxide formation on the surface. © 1990, The Electrochemical Society, Inc. All rights reserved.