During this period, he decided to abandon his studies at the Faculty of Law at the University of Athens and devote himself exclusively to music.
After World War II, he continued his studies at the Mozarteum in Salzburg and graduated with piano and conducting diplomas in 1948–1949.
In Germany, he gave 80 recitals, in co-operation with the American Information Center, following his performance of Aaron Copland's Piano Sonata in its European premiere.
[2] In December 1954, he discovered several lost Skalkottas manuscripts in a second-hand bookshop in Berlin, for the Octet, two String Quartets, and the Piano Concerto No.
A 1959 tour in the Soviet Union included a meeting with Heinrich Neuhaus, who inspired Hadjinikos in the career direction of teaching.
He continued his scholarship, advocacy and performances of the music of Skalkottas,[5] including conducting the world premiere of the Piano Concerto No.
Some of his pupils who studied closely with him for years, included Gilbert Biberian, Paul Galbraith, Kostas Grigoreas, Richard Ward-Roden, Teodor Currentzis, Trefor Smith, Robyn Koh, Dafydd Bullock, Smaro Gregoriadou, Christos Marinos, Nikos Adraskelas, and Yiorgo Moutsiaras.