There are various methods of extracting oil from the seed germs. The germ is the small germinating part of the seed, which grows into a new maize plant. These germs are rich in nutrients and oils. The best oil in terms of health benefits is the cold pressed oil. However, it has a much lower yield than the combination expeller and solvent process.

The production of corn oil from the germ of corn kernels has been practiced on a commercial scale for probably a quarter of a century. From the time the degermination of corn became an integral operation in the hominy, starch, and glucose industries, the disposition of the germ has been a deciding factor in the economics of these processes.

At first the general practice was to dispose of the germ material by adding it to feed products, but as the demand for vegetable oils increased, for both edible and technical uses, it was found profitable to expel the oil from the germ, and in recent years when oils have been high in price the production of corn oil has become one of the important phases of the corn-products industries.

Generally, all corn oil is expeller-pressed, then solvent-extracted using hexane or 2-methylpentane. The most common process of making corn oil involves expeller pressing. The oil is then treated with a solvent. The solvent is evaporated from the corn oil, recovered, and re-used. After extraction, the corn oil is then refined by degumming and/or alkali treatment, both of which remove phosphatides. Alkali treatment also neutralizes free fatty acids and removes color. Final steps in refining include winterization or the removal of waxes, and deodorization by steam distillation of the oil at 232–260 °C (450–500 °F) under a high vacuum. Some specialty oil producers manufacture unrefined, 100%-expeller-pressed corn oil.

There are also Organic Corn Oil, which is produced by cold pressing. A few producers make 100 % pure unrefined corn oil which is extracted using Cold Pressed Method. This is an expensive method and yield is very low than other corn oils, but it is natural and organic. This is a more expensive product since it has a much lower yield than the combination expeller and solvent process, as well as a smaller market share. However, there is growing demand for Organic Corn oil as well.