Siershahn is an Ortsgemeinde – a community belonging to a Verbandsgemeinde – in the Westerwaldkreis in Rhineland-Palatinate, Germany.

Allocation of seats in the municipal council:[3] Siershahn's biggest firm, and the one richest in tradition is Cera Tech (formerly Keramchemie), still employing most of the villagers.

Siershahn has several bypass roads so that heavy vehicles do not drive through the community as they once did.

Siershahn was once an important railway hub between Limburg, Gießen and Cologne.

The nearest InterCityExpress stop is Montabaur station on the Cologne-Frankfurt high-speed rail line.