The main aim of the PASSEQ (Passive Seismic Experiment in TESZ) is an investigation of the seismic structure of the mantle in TESZ (Trans-European Suture Zone) in Central Europe, between young Paleozoic platform of the Western Europe and much older Precambrian East European platform. The knowledge of deep structure of the TESZ is very important for understanding the tectonic processes in Europe. Thanks to very good knowledge of seismic structure of the crust from deep seismic sounding experiments POLONAISE’97, CELEBRATION 2000 and SUDETES 2003 it is possible to make very good crustal corrections which are necessary for mantle investigations.