Assuming you mean JAR OPS, 1/3.125 says that the following must be carried on each flight:
Certificate of Registration
Certificate of Airworthiness
Noise Certificate (may be a copy)
Air Operator Certificate (may be a copy)
Aircraft Radio Licence
Third party liability Insurance Certificate(s) (may be a copy)
In case of loss or theft, the operation may continue until the flight reaches the base or a place where replacement documents can be provided.
That's basically what is required by ICAO Art 29, but don't forget relevant parts of the Ops manuals (1/3.120) and other stuff in 1/3.120, namely:
Operational Flight Plan with at least the information in JAR OPS 3.1060*
Tech Log with at least the information in JAR OPS 3.915(a)
Details of the filed ATS flight plan
Appropriate NOTAM/AIS documentation
Appropriate meteorological information
Mass and balance documentation as per Subpart J
Notification of special categories of passenger, like security personnel (if not considered as crew), handicapped people, inadmissible passengers, deportees and people in custody
Notification of special loads, including dangerous goods, with written information to the commander as per JAR OPS 3.1215(d)
Current maps and charts and associated documents as per JAR OPS 3.290(b)(7)
Any other documentation which may be required by the States concerned, such as cargo or passenger manifest, etc
Forms for reporting requirements
Phil