The new plant is expected to be completed by the end of 2021, Motor Oil said in a filing to the Athens Stock Exchange late on Wednesday.
It will boost the company's output of value-added products gasoline, kerosene and hydrogen, it said.
Deputy Managing Director Petros Tzannetakis said the project is estimated to generate an additional EBITDA of 90-100 million euros per year, based on relatively conservative assumptions.