A basic oxide is an oxide that either

• reacts with water to have a proton transferred to it
• reacts with an acid to form a salt.

Examples include:

• Sodium oxide which reacts with water to produce Sodium hydroxide.
• Magnesium oxide which reacts with water to form Magnesium hydroxide.
• Copper(II) oxide which reacts with Nitric acid to form Copper nitrate and water.
• i.e. CuO + 2HNO₃ → Cu(NO₃)₂ + H₂O

Basic oxides are oxides of metals.

See also

• Acidic oxide
• Amphoteric oxide