Depending of their metasomatic history or geodynamic origin OH stretching bands of lithospheric pyroxenes in the frequency range 3000 – 3700 cm-1 show different signatures. Pyroxenes from continental lithosphere having undergone “wet” metasomatism have distinct signature compared to continental pyroxenes having undergone “dry” metasomatism. Pyroxenes from oceanic lithosphere have a third type of signature and a fourth type can be identified in xenoliths from island-arcs. We present recent analyses of xenoliths and a review of the literature showing that the phenomenon is widely distributed among continents and oceans. It shows that the phenomenon affects simultaneously opx and cpx and pyroxenes from various lithologies: peridotites, pyroxenites and granulites. For instance, in continental lithosphere, type I signature with OH bands at 3600 and 3415 cm-1 for opx and 3635 and 3445 cm-1 for cpx dominate pyroxenes affected by “wet” metasomatism; while type II with OH bands at 3570 and 3515 cm-1 for opx and 3595 and 3515 cm-1 for cpx dominate pyroxenes affected by “dry” metasomatism. Opxs from oceanic lithosphere have signatures of type III with OH spectra dominated by the band at 3415 cm-1 with a smaller contribution of the bands at 3520, 3570 and 3200 cm-1. Island arc xenoliths show two types of signatures type I but also a type IV with OH spectra dominated by the bands at 3545, 3520, 3300 and 3060 cm-1. It is also interesting to notice that most xenoliths from hot spots directly under oceanic lithosphere have pyroxenes with type I signature. Hot spot modified the OH-signatures of the oceanic lithospheric mantle .In all these observations it was not possible to correlate the signatures with a specific major, minor or trace element and the exact nature of the signatures remains to be identified. Nevertheless, these OH signatures are representative of specific lithospheric events and offer a potential new benchmark for the study of lithosphere-fluid interactions.