| Country | Action | Action Date | Effective Date |
|---|
| AUSTRIA | Accession | 14/10/1961 | 14/10/1961 |
| BELGIUM | Signature | 25/09/1952 | 25/09/1952 |
| CROATIA | Accession | 24/04/1999 | 24/04/1999 |
| FRANCE | Signature | 25/09/1952 | 25/09/1952 |
| GERMANY | Accession | 27/10/1956 | 27/10/1956 |
| GREECE | Accession | 03/10/1959 | 03/10/1959 |
| HUNGARY | Accession | 15/10/1999 | 15/10/1999 |
| ITALY | Accession | 04/10/1958 | 04/10/1958 |
| LUXEMBOURG | Signature | 25/09/1952 | 25/09/1952 |
| NETHERLANDS THE | Signature | 25/09/1952 | 25/09/1952 |
| POLAND | Accession | 09/10/1998 | 09/10/1998 |
| PORTUGAL | Accession | 13/10/1973 | 13/10/1973 |
| SPAIN | Accession | 13/10/1974 | 13/10/1974 |
| SWITZERLAND | Signature | 25/09/1952 | 25/09/1952 |
| TURKEY | Accession | 23/12/1953 | 23/12/1953 |
| UNITED KINGDOM | Accession | 11/10/1996 | 11/10/1996 |
| UNITED KINGDOM | Withdrawal | 22/08/2013 | 22/02/2014 |