The adsorption phase Mo(110) - is structurally analysed by means of low-energy electron diffraction (LEED). A close theory - experiment fit (Pendry R-factor R = 0.16) allows the determination of both a near-threefold-coordinated adsorption site and the detailed reconstructive atomic movements induced in the substrate. The latter are rather complex: in the top Mo layer, hydrogen-coordinated atoms are pulled out of the surface with respect to uncoordinated atoms, leading to a total layer buckling amplitude of 0.06 Å. The second substrate layer is also buckled (0.03 Å) with, however, the Mo atoms below the hydrogen atoms pushed into the surface. The first two interlayer distances relax in the direction of the bulk-like-terminated substrate, as frequently observed for hydrogen-covered surfaces. Yet, compared to the case for Fe(110) - , the induced buckling of top-layer substrate atoms is different in sign (though similar in magnitude), in spite of practically the same adsorption site being obtained, the structural symmetry of the substrate being the same, and the same sign of work-function change being involved. This indicates a delicate balance between structural and electronic material-specific properties.