The interfacial mechanical properties of two systems, SiOx/Au and SiOx/Cu, were measured by a modified periodic cracking method. The state of stress in the SiOx-coated metal wires with cylindrical symmetry were analyzed using a classic model of continuum elasticity. Experimentally, the measurement was carried out by a uniaxial tensile test. Specimens for the tensile test were prepared by depositing a thin layer of SiOx on the metal wires by a plasma enhanced chemical vapor deposition (PECVD) technique. After tensile loading, it was found that the fracture morphology of the SiOx coating depended upon the bonding strength of the interfaces. For a weak interface such as SiOx/Au with a measured bonding strength of 0.230 MPa, debonding at the interface prevailed and most of the cracks in the SiOx coating were inclined to the tensile axis by 45 degrees. In contrast, cracks in the coating of a strong interface such as SiOx/Cu showed periodicity and were perpendicular to the tensile axis. The bonding strength of the interface was estimated to be, at least, 0.885 MPa, while the ultimate shear strength was measured to be 49.5 MPa.