The first Suburban line was inaugurated on 30 July 2004, using 17 OSE Class 560 DMUs between Larissa Station (Now Athens) and the Airport.

An indirect standard gauge train service between Athens and Corinth started on 27 September 2005 after seven months of testing,[7] with the extension to Kiato following on 9 July 2007.

[8] The service initially used Class 560 diesel multiple units, and had to reverse at Neratziotissa.

[9] The first direct trains between Piraeus and Kiato, which did not have to reverse at Nerantziotissa, ran on 6 July 2008.

[10] From 12 December 2010 to 29 July 2017, electric train services using Class 460 electric multiple units were introduced between Kiato and the Airport, forcing passengers heading to and from Piraeus and Athens to change at Ano Liosia for the diesel service to the cities.