The president's visit was organised on the occasion of the introduction of Dioki's new plant for expandable polystyrene.
The company is planning to invest additional 65 million euros in the future, according to the president of the company's managing board, Zdenko Belosevic.
On this occasion, the company's management voiced concern over plans by the City of Zagreb to increase fees for water supplies.
Although it has its own water purifier and loses 30 percent of water through evaporation, Dioki has to pay 15 million kuna annually for the waste water management to the city.
The total annual amount of utility fees is 22 million, according to Belosevic.
Asked whether he had discussed the Druzba Adria project during his recent meeting with Russian President Vladimir Putin in Zagreb, President Mesic said they had talked about it in general without any concrete agreement.
Mesic said that the Druzba Adria project about the oil pipeline from Russia towards the Adriatic used to be a topical issue before elections and that people who had known little about energy topics raised this question.
The Croatian President reiterated that Croatia must have enough energy supplies from more sources with respect of environmental standards.