The early Pleistocene travertines from Kocabaş in the Denizli Basin (SW Turkey), from which the only known Homo erectus from Anatolia derives, are covered by a succession of lake deposits. So far, the taphonomic history of the site has precluded a detailed palaeoecological analysis. This paper details the sedimentary succession and palaeoenvironmental conditions by analysing the micro- and macropalaeontological species compositions. These data provide direct evidence of the opportunities and limiting factors of the environment inhabited by hominins during the early Pleistocene. Four distinctive lithostratigraphic units are recognized in the Quaternary succession, consisting of: Lower Travertine, Lower Conglomerates, Upper Travertine, and Upper Conglomerates. These units correspond to an alternation of lacustrine limestone, fluvial-lacustrine siliciclastic deposits and subaerially precipitated travertine accumulations. The age of the succession is constrained by cosmogenic nuclide concentration, palaeomagnetic measurements and large mammal biostratigraphy which suggest deposition occurred between ∼1.6 and 1.2 Ma. The travertine succession contains a moderately diverse macromammal fauna, including Homo erectus, decapod crustaceans and leaf imprints. The herbivore association likely dwelled in a mixed landscape during temperate and humid climatic conditions, supported by negative δ¹⁸O values from analysed gastropod and bivalve shells. The presence of an anomalohaline lake is indicated by an abundant and well-preserved ostracod community, consisting of alkaline tolerant taxa and freshwater genera further supported by the presence of cardiid bivalves.