This issue from the topic series “Corrosion” contains articles published by Trans Tech Publications in the 2019 - 2020 years. The volume “Corrosion. Protection of Structural Metals and Alloys (2019-2020)” is the second book on this topic and presents readers with a wide range of research results and engineering solutions in providing anti-corrosion protection of structural metals, alloys, and engineering objects. This collection will be valuable and exciting to a broad audience of researchers and engineers from various modern manufacturing areas.