We investigate the ferromagnetic resonance response of palladium-cobalt bi-layer thin films to hydrogen charging at atmospheric pressure. We find that hydrogen absorption by the palladium capping layer results in the narrowing and shifting of the ferromagnetic resonance line of the underlying cobalt. We explain the observed phenomena as originating from reduction in the spin pumping effect and from variation in the magnetic anisotropy of the cobalt layer through an interface effect. The shift of the resonance frequency or field is the easiest to detect. We utilize this to demonstrate functionality of the bi-layer film as a hydrogen sensor. © 2013 American Institute of Physics.