Members
Since its foundation, ENTSOG Member TSOs have provided wide coverage of the European gas market. In addition, ENTSOG's Articles of Association were modified in December 2010 to admit TSOs from EU countries currently derogated from the Third Energy Package, such as the Baltic States, as Associated Partners. This allowed for participation in ENTSOG activities.
In February 2011, TSOs from Third Party countries (candidates for EU accession, members of the Energy Community or EFTA) interested in following development of the network codes were also admitted to the Association as Observers.
ENTSOG was created on 1 December 2009 and is now comprised of:
42 TSO Members, 2 Associated Partners and 9 Observers.
Members
| Austria |  | Gas Connect Austria GmbH | Floridsdorfer Haupstrasse 1 | |||
| Austria |   | TAG GmbH (Trans Austria Gasleitung GmbH) | Wiedner Hauptstrasse 120-124 / 1050 Wien www.taggmbh.at | |||
| Belgium |  | Fluxys Belgium S.A. | Avenue des Arts 31 1040 Bruxelles www.fluxys.com | |||
 | Interconnector Limited | 4th floor, 15-16 Buckingham street, London, WC2N 6DU | ||||
| Bulgaria |  | Bulgartransgaz EAD | 66. Pancho Vladigerov Blvd. | |||
| Croatia |  | Plinacro | Savska 88A 1 | |||
| Czech Republic |  | NET4GAS, s.r.o. | Na Hřebenech II 1718/8 | |||
| Denmark |  | Energinet | Tonne Kjærsvej 65 | |||
| Finland |  | Gasgrid Finland Oy | Keilaranta 19D | |||
| France |  | GRTgaz | 6 rue Raoul Nordling | |||
| France |  | TERÉGA | Espace Volta | |||
| Germany |  | bayernets GmbH | Poccistraße 7 | |||
| Germany |  | Fluxys TENP GmbH | Elisabethstrasse 11 | |||
| Germany |  | GASCADE Gastransport GmbH | Kölnische Straße 108 | |||
| Germany |  | Gastransport Nord GmbH | Cloppenburger Straße 363 | |||
| Germany |  | Gasunie Deutschland Transport Services GmbH | Pelikanplatz 5 | |||
| Germany |  | GRTgaz Deutschland GmbH | Rosenthaler Straße 40/41 | |||
| Germany |  | terranets bw GmbH | Am Wallgraben 135 | |||
| Germany |  | Thyssengas GmbH | Emil-Moog-Platz 13 44137 Dortmund www.thyssengas.com | |||
| Germany |  | NEL Gastransport GmbH | Kölnische Strasse 108-112 | |||
| Germany |  | Nowega GmbH | Nowega GmbH | |||
| Germany |  | Ontras Gastransport GmbH | Maximilianallee 4 | |||
| Germany |  | Open Grid Europe GmbH | Kallenbergstr. 5, 45141 Essen | |||
| Greece |  | DESFA S.A. Hellenic Gas Transmision System Operator S.A. | 357-359 Messogion Av., | |||
| Hungary |  | FGSZ Natural Gas Transmission Private Company Limited By Shares | Tanácsház u.5. 8600 Siófok www.fgsz.hu | |||
| Ireland |  | Gas Networks Ireland | Gasworks Road | |||
| Italy |  | Infrastrutture Trasporto Gas SpA | Piazza Santa Barbara 7 | |||
| Italy |  | Snam Rete Gas S.p.A. | Piazza Santa Barbara 7 | |||
| Italy |  | Società Gasdotti Italia S.p.A. | Via dei Salci, 25 03100 Frosinone (FR) http://www.gasdottitalia.it | |||
| Latvia |  | Conexus Baltic Grid | AS Conexus Baltic Grid | |||
| Lithuania |  | AB Amber Grid | AB Amber Grid | |||
| Luxembourg |  | Creos Luxembourg S.A. | Rue de Strassen 105 | |||
| Netherlands |  | Gasunie Transport Services B.V. | Concourslaan 17 | |||
| Netherlands |  | BBL Company V.O.F. |
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| Poland |  | Gas Transmission Operator GAZ-SYSTEM S.A. | ul. Mszczonowska 4 | |||
| Portugal |  | REN - Gasodutos, S.A. | Estrada Nacional 116 | |||
| Romania |  | Transgaz S.A. | 1 Pieta Constantin I. Motas square | |||
| Slovakia |  | eustream, a.s. | Votrubova 11, | |||
| Slovenia |  | PLINOVODI d.o.o. | Cesta Ljubljanske brigade 11b | |||
| Spain |  | ENAGAS TRANSPORTE S.A.U | Paseo de los Olmos 19 | |||
| Spain |  | Regasificadora del Noroeste S.A. | Punta Promontorio s/n | |||
| Sweden |  | Swedegas AB | Kilsgatan 4 |
Associated Partners
| Estonia |  | Elering AS | Kadaka tee 42 12915 Tallinn Estonia https://elering.ee/en |
| Switzerland |  | Trans Adriatic Pipeline AG | Lindenstrasse 2, |
Observers
| Albania |  | Albgaz |
Blv "Zhan Dark", Nr.3 |
| Bosnia and Herzegovina |  | BH-Gas Ltd. Sarajevo | Obala Kulina bana 8 |
| North Macedonia |  | GA-MA AD | Blvd. "Sv. Kliment Ohridski" 54 |
| Moldova |  | Moldovatransgaz | MD-5200, Р. Молдова |
| Norway |  | Gassco AS | PO Box 93 |
| Switzerland |  | Swissgas - Schweizerische Aktiengesellschaft für Erdgas | Grütlistrasse 44 |
| Switzerland |  | Erdgas Ostschweiz AG |
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| Switzerland |  | Transitgas AG | Horüti 12 |
Ukraine
|  | LLC Gas TSO of Ukraine | Liubomyra Huzara av. 44 03065 Kyiv https://tsoua.com/en/ |