Kelsterbach (German: [ˈkɛl.stɐˌbax] ⓘ) is a town in Groß-Gerau district in Hessen, Germany, part of the Frankfurt Rhein-Main urban area.

Kelsterbach borders in the west on the Hattersheim am Main constituent community of Okriftel (Main-Taunus-Kreis), in the north on the Frankfurt am Main (district-free city) constituent communities of Sindlingen, Höchst and Schwanheim, in the east and south on the airport lands, and in the southwest on the town of Raunheim.

Until a short time ago, Kelsterbach was deemed to be the place where Europe's earliest anatomically modern humans had been found.

A Cro-Magnon skull that became known as the "Lady from Kelsterbach", reputedly dated to 32,000 years ago, vanished without a trace amid the scandal over the anthropologist Reiner Protsch, and was likely a fake.

All the archaeological analysis considered as a whole has yielded the assumption that there was a Middle to Late Bronze Age settlement some 10 to 15 m above the Main.

In 1970, bits of tile and coins found in the northeast part of the municipal area were enough to prompt extensive digs in 2004 and 2005 by the Goethe University's Institute for Archaeological Sciences.

In 1479, Kelsterbach along with the whole County of Katzenelnbogen passed to the Landgraviate of Hesse, and through division of inheritance in 1567, to Hesse-Darmstadt, whose history was shared thereafter by this rather insignificant farming village.

In the second half of the 20th century, the town lost quite a bit of its area to the gradually expanding airport on its southern limit.

This development continues, bringing the town's independence ever more into question, as Kelsterbach is being more and more cut off from the rest of Groß-Gerau district.

The municipal elections on 26 March 2006 yielded the following results: Note: WIK and EUK are citizens' coalitions, with the former being "green"-oriented, and the latter being an initiative of EU foreigners.

Kelsterbach's civic coat of arms might heraldically be described thus: In sable an oak tree with four leaves argent and three acorns Or.

Owing to the Frankfurt Airport's expansion, the power lines leading to the substation from the south have had to be relocated several times.

In preparation for building the Northwest Runway, the substation was being moved and modernized with gas insulated switchgear, power lines undergrounded or removed.

Aside from many cultural events, Kelsterbach is known far beyond its limits for its traditional church fair (Kerb) on the first Sunday in September, and for its Old Town Festival (Altstadtfest) a week later.

Serving as local recreation areas are the well designed Main riverside, the South Park (Südpark), which is heavily frequented in summer, and an extensive town forest.

Besides the Main riverside, these areas are being demanded by Fraport AG for the foreseen Frankfurt Airport expansion (as of April 2006).