There has been studied an extraction of gallium and aluminium at their joint presence in aluminate-alkali solutions. The conditions of extractional separation of gallium and aluminium from alkali solutions dependent on the correlation of their concentrations have been determined. The process of re-extraction of these metals from organic phase has been investigated. There has been elaborated and offered a new principal technological scheme of extractional separation of gallium and aluminium with the further concentration of gallium from aluminate-alkali solutions in aluminium oxide production.