Most melting and holding furnacesMelting and holding furnaces in casthousesCasthouse are heated with gas burners. These gas burners give high concentrations of water vapourWater vapour in the atmosphere. The concentration of water vapourWater vapour is dependent on both burner configuration and furnaceFurnace design (excess air entrainment), as well as fuel. The issue will become even more relevant if more hydrogenHydrogen is being used in burners in a push towards decarbonisation. High levels of water vapourWater vapour have previously been shown to correlate with high levels of dissolved hydrogenHydrogen and this is supported in this article. This paper shows the dynamic transport of hydrogenHydrogen absorption into the melt and hydrogenHydrogen evaporation out of the melt. Mass transfer coefficients for both absorption and evaporation are presented, and the measurementsMeasurements show that absorption of hydrogenHydrogen from water vapourWater vapour into the melt is faster than evaporation.