The exhibition was opened by European Parliament Vice President Mairead McGuinness, a MEP from Ireland, and the opening ceremony was attended, among others, by representatives of the Zagreb Archdiocese.
Bishop Ivan Sasko said that Stepinac was "an example of a European who lived the values of the culture of Christianity that has largely shaped Europe's identity."
"His service made him permanently exposed... not only to the public but to the blows of three fatal ideologies - fascism, Nazism and communism, which marked a large part of the 20th century in Europe," said Sasko.
"At the time of communism, his good deeds were not spoken about and were covered up... the evidence of his exposure did not disappear despite its having been terribly distorted and manipulated," Sasko said, adding that after communism one could freely talk about Stepinac but that decades of propaganda had caused damage.
The exhibition will be open until June 17.
On Wednesday, a conference on Stepinac's humanitarian work will be held.
The Blessed Alojzije Stepinac became Zagreb Archbishop in 1937. He was named a cardinal in 1953 and Pope John Paul II beatified him in the Croatian shrine of Marija Bistrica on 3 October 1998. He is expected to be canonised soon.