Sodium hydroxide, also known as lye or caustic soda, is a highly caustic chemical compound with the formula NaOH. It is a white solid that readily absorbs moisture and dissolves in water, producing an alkaline solution. Sodium hydroxide is produced industrially by the electrolysis of brine (sodium chloride solution).

So, the elements making up sodium hydroxide are sodium (Na), oxygen (O), and hydrogen (H).