DVGW CERT GmbH is releasing certification programme ZP 5101: “Compatibility and permeation properties of elastomer materials for seals and membranes in gas appliances and installations in relation to hydrogen for a content of up to 100 Vol% H2”. The certification programme enters into force on 19/11/2021. It supplements the existing testing for elastomer materials for natural gas so that they can also be tested and certified for H2 blending and 100 Vol% hydrogen as part of the conformity assessment. This certification programme is yet another module in the gradual expansion of the hydrogen certification process.