On June 6, 1953, Malez began his professional career as an assistant in the professional class of Academician Marijan Salopek in the Geological-Paleontological Collection and Karst Laboratory of the JAZU (Yugoslav Academy of Art and Science) (The Collection & Laboratory unit was officially active since March 24, 1955) Its purpose was geological–paleontological, hydrological and speleological research of the karst, and archive development. When it redirected its research to palaeontology of the vertebrates, and quaternary geology, the Academy on July 25, 1953, renamed the 'Paleontological Collection Unit' to the 'Institute for Quaternary Palaeontology and Geology', with Malez as its first director. In 1978, the Academy established a Research Center and its first director was also Malez. He stayed in this position until his retirement in March 1990. He began his associate JAZU (HAZU) membership in 1968, and a full membership in 1979. Malez was credited with the development of the Collection and Library of the Institute for Quaternary Palaeontology and Geology. In 1989, he was chosen to receive associate membership of the Austrian Academy of Sciences. He worked with many foreign scientists and experts, especially Austrian and Soviet. Malez cooperated with several others on making the geological map of Yugoslavia, and on the pedological map: he cooperated with Dr Teofil Slišković in interpreting the vertebrate fossil finds and the quaternary geology of the Bosnia Herzegovina, then with Ivan Rakovec (doyen of Slovenian quaternary research), Dr Risto Garevski, during the analyses of the tertiary vertebrate faunas of Macedonia, Erich Thenius and Helmuth Zapfe in Vienna, Herbert Ullrich from Berlin, Henry de Lumley from Paris, Fred Smith from the US and Ann Forsten from Helsinki. Following his research inclinations and scientific obligations over the years, he visited Lebanon, Egypt, Tunisia, Morocco, Kenya, Tanzania, Zambia, China and Mexico. World-famous media such as National Geographic and the BBC showed an interest on Malez's research. As well as performing scientific research, Malez served as Editor in Chief for all issues of the whilom journal Razred za prirodne znanosti Akademije and sat on a number of other magazine editorial advisory, and inter-academic, boards. From the early 1950s he started publishing scientific – popular articles about speleology and geology in the magazines Naše Planine and Speleolog. Malez published over 200 papers, and 14 speleological studies and analyses, on speleology that covered cave genesis, and underground and surface karst phenomena. Malez was also an associate professor at the Faculty