The sequence in which the Member States of the European Union are listed in various contexts - including order of signatures on treaties, lists of members of bodies, and the order in which countries hold the Presidency of the Union1 - is determined by the name of the country in its own official language. Thus, as at the time of writing, we have:

Currently Belgium is the only country with more than one official language treated on an equal footing (since Ireland voluntarily forewent the use of Irish as a working language despite its constitutional status); should trilingual Switzerland ever join the EU there would have to be a compromise since "Suisse" and "Schweiz" come before "Sverige" but "Svizzero" falls after it ...

Likewise the official languages of the Union are listed in the alphabetical order of their own names in the language itself. This order is also always used when EU documents, web pages, etc. have multilingual captions.

  1. The six-month terms of the rotating presidency of the Council of Ministers are determined by alternating two cycles, first in the protocol order as shown and then once in the same order but with each pair of countries reversed. There have been some recent exceptions to allow the most recent accessions (Austria, Finland and Sweden) to have a turn.
  2. At the request of the Spanish government, the Spanish language is always referred to as "español", "Spanish" and their cognates in other languages, but keeps the first place in the list that "Castilian" gives it.