The interlayer exchange coupling ͑IEC͒ and the magnetic anisotropy of Co/Ru͑0002͒ hcp superlattices, produced by magnetron sputtering, were studied by ferromagnetic resonance ͑FMR͒. The main mode and a secondary mode, with a higher resonance field, were identified in the perpendicular FMR spectra. The secondary mode is attributed to the resonance of the bulk of Co magnetic layers while the main mode is associated with the Co/Ru interfacial phase. The linewidth dependence of the main FMR mode on the Ru thickness clearly reproduces the oscillations of the IEC between Co layers. These oscillations are attributed to the effects of lateral inhomogeneities of the IEC strength and have a period of about 12 Å. Moreover, they are in good agreement with magnetoresistance and magnetization measurements performed in the same samples. The dependence of the effective anisotropy constants on the Co layer thickness leads to the volume and surface anisotropy constants of K V = −1.10ϫ 10 7 erg/ cm 3 and 2K s = 0.95 erg/ cm 2 , respectively, and also to a critical Co thickness of approximately 9 Å below which the magnetization is oriented perpendicular to the plane of the film.