| Country | Action | Action Date | Effective Date |
|---|---|---|---|
| AUSTRIA | Signature | 16/12/1955 | |
| BELGIUM | Signature | 16/12/1955 | |
| BELGIUM | Ratification | 28/05/1956 | |
| FRANCE | Definitive Signature | 16/12/1955 | |
| GREECE | Signature | 16/12/1955 | |
| HUNGARY | Accession | 30/07/1962 | |
| ITALY | Accession | 12/02/1958 | |
| LUXEMBOURG | Signature | 16/12/1955 | |
| LUXEMBOURG | Ratification | 03/06/1957 | |
| MONTENEGRO | Succession | 23/10/2006 | |
| NETHERLANDS THE | Signature | 16/12/1955 | |
| NETHERLANDS THE | Ratification | 31/01/1958 | |
| POLAND | Accession | 29/10/1958 | |
| SLOVENIA | Succession | 06/07/1992 | 25/06/1991 |
| SPAIN | Accession | 09/06/1960 | |
| UNITED KINGDOM | Accession | 16/05/1966 | |
| VATICAN CITY | Accession | 01/10/1956 | |
| YUGOSLAVIA | Signature | 16/12/1955 | |
| YUGOSLAVIA | Ratification | 19/03/1957 | |
| YUGOSLAVIA, FEDERAL REPUBLIC OF | Succession | 12/03/2001 | 27/04/1992 |