It operates between the Hesse state capital Wiesbaden and the southern Offenbach rural district serving the densely populated area along the Main river.

With a route length of over 70 km (43 mi), 30 stations and a journey time of 87 minutes, it is the longest S-Bahn service in the Rhine-Main area.

The western branch of the service starts at the central station of Wiesbaden and utilises the oldest railway route of the Rhine-Main area running between Mainz-Kastel and Frankfurt-Höchst parallel to the Main and the Taunus mountains from which the railway line derived its name.

Further extensions of the tunnel followed in 1983 (Konstablerwache) and 1990 (Ostendstraße and Lokalbahnhof) so that the Südbahnhof (South station) became the service's eastern terminal.

In 1992 the eastern branch of the Citytunnel to the Mühlberg station was opened and the S1 started operation in this section shutting down its service to Lokalbahnhof and Südbahnhof.