1) Microprocessors operation & utilization (C.E.R.N, Geneva, 1981).
2) Minicomputers programming and techniques (C.E.R.N, Geneva, 1982).
3) VAX/VMS System Management (DEC, Valbonne France, 1987).
4) VAX ACMS Application Programming (DEC, Munich, 1990).
5) Router Operations Management (Wellfleet, London, 1994).
6) Advanced IP Routing Technology (Bay Networks, Valbonne FR, 1996).
7) Lotus Notes Basic Concepts (Byte, Athens, 1996).
8 ) Lotus Notes Administration (Byte, Athens, 1997).
9) Introduction to ATM FORE switch configuration (Anco, Athens, 1998).
10) Advanced ATM FORE switches configuration (Anco, Athens, 1998).
11) Cisco Catalysts 1900, 5000 switches configuration (Anco, Athens, 1998).
12) Network Management System Spectrum (Anco, Athens, 1998).
13) ISDN & PBX (Anco, Athens, 1999).
14) Solaris System Administration I & II (SUN, Athens, 2000).
15) Creating & Configuring a Web Server using Microsoft IIS 4.0 (Microsoft Certification, ITEC, Athens, 2000).
16) Secure Web Access using Microsoft Proxy Server 2.0 (Microsoft Certification, ITEC, Athens, 2000).
17) Cisco routers (CCNA Certification, Cisco, Athens, 2002).
18) Oracle database special subjects (National Centre of Public Administration, TEIA, Athens, 2003).