<p>Volcanic rocks are widely distributed within the palaeozoic sedimentary rock sequences of the Rhenish Massif. New geochemical analyses of these volcanics have been evaluated, allowing a distinction between intraplate volcanism and subduction-related volcanism based on trace elements and Rare Earth Elements. Subduction-related volcanism began in the Silurian and continued through the entire Devonian and into the early Carboniferous. The trigger for the volcanic activities was the subduction of the Rheic Ocean northward beneath the southern margin of Avalonia. A magmatic arc had developed above the subduction zone, where explosive eruptions occurred throughout the entire timespan. To the north of this arc the Rhenohercynian back-arc basin opened from the Lower Devonian onwards, whereby Avalonia was split into a northern and a southern part. As a result of the rifting of the continental crust of the southern Avalonian shelf area, intense alkaline bimodal intraplate volcanism began in the Givetian, contemporaneous with the subduction-related volcanism, persisting until the early Frasnian. After an interruption the Middle–Upper Devonian Cycle of intraplate volcanism ended in the highest Famennian with the eruption of primitive basaltic magma. Due to the roll back of the subduction zone, Southern Avalonia migrated increasingly southward with simultaneous expansion of the back-arc basin. A new cycle of intraplate volcanism began in the early Carboniferous, which is characterised by tholeiitic magma. At the end of the Lower Carboniferous Cycle primitive alkali basaltic melts rose from deep mantle sources thereby transporting numerous, partly very large spinel-lherzolitic mantle xenoliths. The products of both cycles of intraplate volcanism occupy large areas in the Lahn and Dill-Eder Syncline (Lahn-Dill- and Kellerwald regions) and the Waldeck Syncline. Subvolcanic intrusions and feeder dykes in the northern part of the Taunus Anticline and the northeastern Siegen Anticline give evidence for the widespread distribution of volcanism beyond the present-day limits imposed by erosion. The palaeozoic volcanism ended with the closure of the oceanic areas and the following continent-continent collision of Laurussia with Armorica and Gondwana.</p>