Epoxyethane is similar to ethene, with the exception that it does not have a double bond. Instead, the double bond has been saturated such that each carbon atom now bonds to the same oxygen atom. The formula is C₂H₄O. Each carbon atom is bonded with the central oxygen, and so the oxygen has two bonds with each carbon atom.

Epoxyethane has a boiling point of 10 degrees Celsius, making it a gas at room temperature. It is colourless, flammable, toxic, and affects the nervous system when inhaled.

Epoxyethane is normally manufactured from ethene. This is reacted with oxygen in the presence of a silver-based catalyst, at 250-300 degrees Celsius. Pressures used are in the region of 1-2MPa.

Epoxyethane is also known as ethylene oxide, which also illustrates its normal method of production. Its systematic name is oxiran.

Its reactions are ring openings by nucleophiles. In industry, epoxyethane is reacted with water in the presence of a sulfuric acid catalyst. A ten-fold molar excess of water is used to obtain ethane-1,2-diol, also known as ethylene glycol:

HOCH₂CH₂OH

Despite the large excess of water, various types of polyethylene glycol (PEG) are still formed as secondary products. The degree of polymerization increases as a smaller proportion of water is used:

n(CH₂CH₂O) + H₂O -----> HO(CH₂CH₂O)_nH

For example, under the right conditions it can give diethylene glycol (HOCH₂CH₂OCH₂CH₂OH), triethylene glycol, etc.

Similarly, reaction with ammonia can yield ethanolamine, diethanolamine, or triethanolamine.