December 23, 2025 [SeeNews]- Croatian oil and gas company INA said on Monday its key Rijeka refinery upgrade project has entered the final phase of implementation and the entire complex will be ready for commissioning in the first quarter of 2026.

The investment, valued at nearly 700 million ($824 million), represents the largest single investment in INA’s history and one of the most significant industrial projects in Croatia, with more than half of the work carried out by domestic contractors, the company said in a press release.

Construction works on the key systems of the new processing units have been completed, and comprehensive inspections and testing activities are currently underway as a condition for hot commissioning and full operational readiness, it added.

The project includes the construction of a delayed coker unit, modernisation of existing units, as well as the development of a new port, storage silos, an enclosed coke handling and transportation system, and a new high-capacity substation – the largest in the country – ensuring a reliable and secure power supply for the new facility.

Once the new delayed coker unit is commissioned, INA will increase production of diesel by up to 30%, or 400,000 tonnes per year, and will boost production of other high-value distillates. Crude oil processing capacity will increase from just over 3.0 million tonnes per year to some 4.0 million tonnes in 2027, when the new unit reaches full capacity.

The new facility will employ 60 staff, including engineers and shift operators. It will substantially contribute to reliable and continuous supply, while significantly reducing the need for imports of petroleum products, primarily diesel, especially during the tourist season when demand peaks, INA added.

Moreover, the production process will eliminate the need for importing vacuum gas oil, which on the European market is predominantly of Russian origin. This further strengthens energy security, reduces dependence on imported feedstocks, and enhances the overall resilience of the system, INA explained.

The company is part of Hungarian energy group MOL.