- 36 Member Countries: Austria, Belgium, Bosnia and Herzegovina, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Montenegro, The Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey, United Kingdom, the former Yugoslav Republic of Macedonia and
- One cooperating state: Israel
According to the COST rules, participation of Member Countries is based exclusively on a voluntary approach. They participate only in mutually agreed Actions, depending on their interest, relevance of joint research and shorter time needed to achieve envisaged results. The achieved results are the property of all participants, who have to provide full funding for agreed research and concerted activities themselves. COST Member Countries merely endorse the Actions by signing a Memorandum of Understanding, thus increasing their importance and providing moral support.