İsdemir, one of OYAK Mining Metallurgy companies, is the third largest integrated iron and steel plant in Turkey by date of establishment and the largest integrated iron and steel plant by long product production capacity. With its 3.5 million tonnes/year hot rolling capacity, which was commissioned in 2008, İsdemir is Turkey's only and largest integrated facility producing long and flat products at the same time.

İsdemir was established on 3 October 1970 in the Payas (Yakacık) region, 17 km from İskenderun, on the Mediterranean coast of southern Turkey. At the time of its establishment, it was built on a total area of 16.75 million m2 (factory area 6.8 million m2 ), including social facilities.

Commissioned in 1975 with a production capacity of 1.1 million tonnes/year of steel bloom, İsdemir's production capacity was gradually increased to 2.2 million tonnes/year in 1984 with the first expansion.

Established with the aim of producing long products such as pig, bloom, billet and construction steels at international quality standards, İsdemir carries out production through coke - sinter - blast furnace - steel mill - continuous casting and hot rolling processes.

In addition to the domestic market, the products are exported to countries all over the world, particularly to Southern Europe and the Middle East.

With the Modernisation and Transformation Investments (MTRI) made at İsdemir, flat product production was started in August 2008 in addition to long products.

Playing an important role in increasing the flat product production capacity, which is vital for the development of the Turkish steel industry, İsdemir produces billet, coil, hot roll and slab. In addition to these products, by-products such as coke, oxygen, nitrogen, argon, ammonium sulphate, granulated slag, tar and benzol are also obtained.

All of İsdemir's shares were transferred to Erdemir by the Privatisation Administration with the Share Transfer Agreement dated 31 January 2002, on the condition that investments were made for the transition to flat production. With the acquisition of Erdemir by OYAK, İsdemir started to operate under the roof of OYAK on 27 February 2006. Currently, 94.87% of İsdemir shares are owned by Erdemir and 5.13% by other owners.

At İsdemir, which adopts the main principle of continuous development, creating a difference in products and services with its sensitivity to the environment by using new technologies, the Modernisation and Transformation Investments (MTI), which were planned in 2002 and started in 2003, were completed and the liquid steel capacity, which was initially 2.2 million tons/year, was increased to 5.3 million tons/year. In addition, the installed facilities have a production capacity of 3.5 million tonnes/year of flat products, 0.6 million tonnes/year of coils and 2.5 million tonnes/year of billet finished products.

Today, İsdemir is the only integrated flat steel producer in Turkey with a liquid steel capacity of 5.8 million tonnes/year, capable of producing flat and long products at the same time.