The crucial effect of the revetment porosity on the wave loading and the response of the structure has been illustrated by Liebisch et al. (2012). Though the revetment porosity may substantially be reduced over design life time (e.g. marine growth, sediment deposition), the porosity is not yet explicitly and adequately considered in the current design practice. Therefore, the primary objective of this study is to improve the knowledge related to the effect of the porosity of a porous bonded revetment for different slope steepnesses on the hydrodynamic processes on and beneath the revetment. To achieve the aforementioned objectives, extensive scale model tests were conducted.