Hrvoje Požar was born in Knin, where he finished elementary school. He attended secondary school first in Šibenik and later in Zagreb, where he graduated in 1934. He graduated from the Faculty of Electrical Engineering in Zagreb in 1939 and became an electrical engineer.
After graduation he worked on various executive positions in electroenergetics. In 1950 he started working part time as a lecturer on the Faculty of Electrical Engineering in Zagreb, and in 1955 he obtained his doctoral degree in technical sciences with the thesis The Size of Hydroelectric Power Plant Building.
He became full professor at the Faculty of Electrical Engineering in Zagreb in 1961, and in 1965 he became associate member of the then Yugoslav Academy of Sciences and Arts. He was the editor-in-chief of the Technical Academy, volumes 6 to 12, till his death.
He performed the duties of the secretary general of the Croatian Academy of Sciences and Arts till his death. He was vice-rector of the University of Zagreb. Together with rector Ivan Supek and vice-rector Nikša Allegretti he was responsible for the establishment of University Computer Centre.
He published over 330 scientific and professional papers, studies, course materials and books from the field of energetics, nearly 30,000 pages in total. To honour Hrvoje Požar, the Government of the Republic of Croatia named the Energy Institute after him.
The book Hrvoje Požar, the Giant of Energetics and Modern University Education 1916-1991 was published in 2003. The book tells the story of his life, his rich career and his important works.