Laser-induced fluorescence spectra of jet-cooled HGeCl, DGeCl, HGeBr, and DGeBr have been obtained using the pulsed discharge technique. The germylenes were produced by an electric discharge through argon seeded with the appropriate monohalogermane (H3GeX or D3GeX). All excited start: vibrational frequencies have been obtained for each of the four molecules. Analysis of the rotational structure of the O-0(0) bands of the <(A)over tilde (1)A "> - <(X)over tilde (1)A'> band system allowed the determination of r(0) structures in the ground and excited states, with the bond angles constrained to previous nb initio values. The results for HGeCl are: r(0) "(Ge-Cl) = 2.171(2) , r(0) "(H-Ge) = 1.592(1) Angstrom, theta(0) "(HGeCl) = 94.3 degrees, r(0)'(Ge-Cl) = 2.146(15) Angstrom. r(0)'(H-Ge) = 1.613(2) Angstrom, theta(0)'(HGeCl) = 114.5 degrees; and for HGeBr: r(0) "(Ge-Br) = 2.329(12) Angstrom, r(0) "(H-Ge) = 1.598(6) Angstrom, theta(0) "(HGeBr) = 93.9 degrees, r(0)'(Ge-Br) = 2.308(1) Angstrom, r(0)'(H-Ge) = 1.615(1) Angstrom, and theta(0)'(HGeBr) = 116.3 degrees. The radiative lifetimes of the <(A)over tilde (1)A "> states of HGeCl and HGeBr have been measured to be 548 +/- 19 ns and 736 +/- 24 ns, respectively.