Originally Posted by totti
In eastern europe at least in Montenegro and Kosovo the Euro is the offical currency.
True on the Montenegro count, and nearly correct on Kosovo count. The Euro is one of two official currencies of the protectorate: the Serbian dinar is also legal tender there. OTOH, the dinar is the only official tender in Serbia, but the Euro is used and accepted (probably because of its loose commonwealth with Montenegro).
The EU at a glance - Travelling in Europe - Money:
The euro is the legal tender for more than 300 million people in Austria, Belgium, Finland, France, Germany, Greece, Italy, Ireland, Luxembourg, the Netherlands, Portugal and Spain. The symbol for the euro is €.
The euro is also used in Andorra, Monaco, San Marino and Vatican City, and in Kosovo and Montenegro in the western Balkans as well as in the Azores, the Canaries, French Guiana, Guadeloupe, Madeira, Martinique, Mayotte, Réunion, and Saint Pierre and Miquelon, which are all part of EU countries using the euro.
There are different thresholds of participation in the EU. EU membership does not entail immediate conversion -- or conversion at all -- to the Euro.
Just to make matters crystal clear, a country can be Schengen but not necessarily an EU member.