The germylynecomplex 2 was obtained by dehydrogenation of a hydrido (hydrogermylene) complex 1 with mesitylisocyanate on heating. A reaction intermediate 3 was also isolated by a room temperature reaction, which was converted into 2 by heating, with elimination of MesNHCHO. A possible mechanism for the formation of 2 was elucidated by kinetic studies and DFT calculations.