Repairing of metallic structures using composite patches bonded with an adhesive layer is more and more common in the aeronautic field. Shear-horizontally polarized (SH) waves are investigated to infer the shear stiffness of the adhesive layer, which is necessarily linked to its shear resistance that is known to be a critical parameter in bonded structures. Numerical simulations are run for selecting the most appropriate SH wave modes, i.e. with higher sensitivity to the shear stiffness of the bond than to other components properties. Original experiments are also made for generating-detecting pre-selected SH wave modes and for measuring their phase velocities. An inverse problem is finally solved, consisting in the evaluation of the shear stiffness modulus of a bond layer between an aluminium plate and a carbon-epoxy composite patch, at different curing time. This work was supported by DGA - CEAT Toulouse, France.