Electroreflectance measurements with the electrolyte technique have been made on various p-type and n-type InAs specimens. The behavior of the spectra and the changeover from p-like to n-like characteristics of the n-type specimens has been studied for various carrier concentrations, electrolytes, and d.c. biasing voltages. The E1 transitions of GaxIn1−xAs alloys close to InAs have then been remeasured and a parabolic variation of E1 and E1 + Δ1 with x obtained.