Steam distillation is considered the best method for the extraction and isolation of essential oils. The plant material is placed in a boiler unit and steam is passed through it. The heat opens the pores of the plant that contains the aromatic molecules or oils. Once open, the plant releases these aromatic molecules and in this state, the fragrant molecules are able to rise along with the steam. The vapors carrying these molecules travel within a closed system towards the cooling device. Cold water is used to cool the vapor. As the vapor cools, it condenses and is transformed into a liquid state. Afterwards, the liquid is collected in a container and as with any type of oil/water mixture, it separates. The oils float towards the top while the water settles below.

The oil is highly condensed and used in aromatherapy. These two processes determine the amount, quality and aroma of oil produced. Approximately 8,000-10,000 kg of Agarwood is needed to produce one liter of oil. Pure Agarwood oil has a light yellow to brownish liquid color appearance, a sweet aromatic scent, a pH value of 6.8 – 13.2 and is soluble in alcohol. The main contents are sesquiterpenes, phenyl ethyl chromones and others like selinene, eudesmene.

The quality of the oil can be tested by using a Gas Chromatography-Mass Spectrometry (GC-MS).