It can be formed by union of the elements. It hydrolyses slowly in water and quickly in mineral acids to form toxic hydrogen selenide gas. The reducing capabilities of the selenide ion make it vulnerable to oxidizing agents. It is advised therefore that it not come into contact with bases.[citation needed]
^Temperature dependence of electrical conductivity and Hall effect of Ga2Se3 single crystal, A. E. Belal, Dr. H. A. El-shaikh, I. A. Ashraf, Crystal Research and Technology, 30, 1, 135 - 139