Between the two Swiss cantons, the line also serves two stations in Germany.

At Zürich HB, trains of the S9 service usually depart from underground tracks (Gleis) 41–44 (Museumstrasse station).

The following stations are served:[4][5] Swiss-German border Swiss-German border As of the December 2022 timetable change,[update] all services are operated by Re 450 class locomotives pushing or pulling double-deck passenger carriages.

[5] Prior to the timetable revision of late 2015, the section of the S9 between Zürich and Uster operated much as today.

However west of Zürich, the trains operated to Zug via Affoltern am Albis.