Only in the photochemical reaction of [W(CO)4(η4-nbd)] and HGeEt3 were two hydride signals detected at the same time by 1H NMR spectroscopy. One signal (septet, at δ -7.63 ppm, 3JH-H(Et) = 1.6 Hz, 1JH-W = 34 Hz) was assigned to the σ-bond complex on the observation of the simultaneous protons of the GeEt3 moiety. The other signal (singlet at δ -2.58 ppm, 1JH-W = 48 Hz) was assigned to a germyl hydride complex of tungsten(II). The disappearance of these hydride signals was accompanied by the formation of triethylgermylnorbornene with high endo-selectivity.