Tüpraş operates four oil refineries, three of which process imported crude. The 11 million tonnes a year Izmit refinery at Izmit in north-west Turkey and the 11 million tonnes/yr Izmir refinery at Aliaga on Turkey's central Aegean coast process crude from global markets delivered by tanker while the 5 million tonnes/yr Kirikkale refinery at Kirrikale in central Turkey processes crude delivered to Turkey's Mediterranean oil hub at Ceyhan and transited to the refinery via a bespoke pipeline. The fourth refinery, the 1.1 million tonnes/yr batman refinery processes crude produced a myriad small oil fields in south-east Turkey delivered to the refinery both via an existing pipeline network and by road tanker.
Tupras also owns a majority stake (79.98%) in the shipping company DİTAŞ and, since 2006, a 40% ownership of petrol retailer Opet.
The company's origins go back to İPRAŞ (İstanbul Petrol Rafinerisi A.Ş.) established by the U.S. Caltex Company (now part of Chevron). In 1983, İPRAŞ and three other publicly owned refineries were brought into state control under the Tüpraş umbrella. Partial privatisation started in 1991, when an IPO sold 2.5% of shares to the public; by 2005 a number of secondary issues had taken this up to 49%. In 2005, a consortium of Koç Holding and Shell bid over $4billion to acquire the 51% interest remaining; this was through a new joint venture company, Enerji Yatırımları A.Ş. The company’s shares were divided among the shareholders as follows: Koç Holding A.Ş. 75%, Aygaz A.Ş. 20%, OPET Petrolcülük A.Ş. 3%, Shell Overseas Investment B.V. 1.9% and the Shell Company of Turkey Ltd. 0.1%.