Catania:

Octocom
Octopus Energy Group
Oliver James Associates Ltd.
Omnissa (Italy) S.r.l.
Oncode
OneOcean Group
OneStream Software LLC
Onyx Technology S.r.L.
Opdenergy
Open Smart Services
Open-Xchange Inc.
openjobmetis
Openjobmetis SpA
OPLIUM
OralPro
Orbyta Group
Orchard Robotics
orienta
Orienta Agenzia per il Lavoro
Orienta SPA
osmosi
otis elevator company
Out in Science, Technology, Engineering, and Mathematics
OutSystems, Inc.
OVERTECH Consulting
ovs
OVS S.p.A.
Oxford Instruments
Oxigent Technologies