CIOS may refer to:
- Cisco IOS, software used on routers and network switches
- Cyprus-Israel Optical System, a cable system linking Cyprus and Israel
- Channel Islands Occupation Society, a military history organisation
- Combined Intelligence Objectives Subcommittee, an organization gathering technical intelligence in Germany after WW2
Cyprus-Israel Optical System (CIOS) is a submarine telecommunications cable system in the Mediterranean Sea linking Cyprus and Israel.
It has landing points in:
- Ayia Napa , Cyprus
- Nahariya , Israel
It has a design transmission capacity of 622 Mbit/s and a total cable length of 250 km. It started operation on 11 April 1994.