Digboi Oil Refinery was established in Digboi in 1901 by Assam Oil Company Ltd. The Indian Oil Corporation Ltd (IOC) took over the refinery and marketing management of Assam Oil Company Ltd. with effect from 1981 and created a separate division. This division has both refinery and marketing operations. The refinery at Digboi had an installed capacity of 0.5 million tonnes per year. The refining capacity of the refinery was increased to 0.65 million tonnes per year by the modernization of the refinery in July 1996. A new delayed Coking Unit of 170,000 tonnes per year capacity was commissioned in 1999. A new Solvent Dewaxing Unit for maximizing the production of microcrystalline wax was installed and commissioned in 2003. The refinery has also installed a Hydrotreater-UOP in 2002 to improve the quality of diesel. The MSQ Upgradation unit has been commissioned. A new terminal was expected to be completed by 2016. It is one of the best oil fields in Assam. Certified