1993 – 1998
Music School of Ján Cikker in Banská Bystrica (guitar – Tibor Neizer, Ivan Frank)
1998 – 2002
Conservatory of Ján Levoslav Bella in Banská Bystrica (Mária Sedláková)
2002 – 2007
Academy of Performing Arts in Bratislava (Jozef Zsapka and his assistant Martin Krajčo)
Susana Prieto, Odair Assad, Anders Miolin, Alvaro Pierri, Walter Feybli, Stefan Hackl, Marco Socías, Luciano Contini and others
Ondrejčák is devoted to the solo guitar as well as performing chamber music. As a soloist or chamber player he introduced himself at domestic festivals (international festival of Peter Michalica Music Under the Diamond Arch, 2004, Banská Bystrica Musical Spring, 2004, Melos-Ethos, 2007 and others), as well as in concerts abroad (Hungary, England, Austria, Czech Republic). In chamber music he cooperates with violinist Andrej Baran, mezzo-soprano Terézia Kružliaková and the Bratislava Guitar Quartet. He is a member of a duo with pianist Zuzana Zamborská (since 2008) and Slovak Guitar Duet with guitarist and lute player Denisa Benčová (since 2005). For the latter there were composed a number of compositions. The Slovak Guitar Duet performed in concert within the cycle Studio of Youth in Slovak Radio that was broadcast in Radio Devín. They also recorded for Slovak Television.