The recent unexpected discovery of a degassing flow from the metal to the hydrogen charging environment, which operates simultaneously with the crude charging flow, has given new interest to the former concepts of internal and external hydrogen, coupled with a new type of cathode protonic reaction. This affects considerably the way permeation experiments are conducted and their results interpreted. This paper proposes a new approach allowing, among other things, to explain what appeared formerly as anomalies, especially in the area of thin membranes.