Abstract Electroluminescence (EL) due to band-to-band transition was observed for n-GaAs in solutions containing peroxodisulfate ions. Digital simulation shows that the observed transient current and EL intensity stimulated by negative potential pulses can be explained by assuming that the surface concentration of S2O82− was zero during potential pulses and that the EL intensity was proportional to the surface concentration of SO4\ewdot(generated by the one-electron reduction of S2O82−). Surface composition change seems to be the main reason for the relation between the potential and EL intensity. A hydrogen evolution reaction reduces the EL efficiency at relatively negative potentials. Although the potential and time had no observed effect on the shape of the EL spectra, the carrier concentration affected the peak position and the full width at half maximum (FWHM) of the EL spectra. For greater carrier concentrations, the wavelength of the EL peak became shorter and the FWHM became larger. These results agree with those reported regarding solid-state luminescence and can be explained by the filling of the conduction band states by electrons (Burnstein-Moss shift).