Dear Readers of Catalysis Reviews: We are very saddened to announce the passing of Prof. Kamil Klier on July 1 at the age of 93 and Prof. Gabor Somorjai on July 7 at the age of 90. Prof. Klier served as a Co-Editor of Catalysis Reviews from 1990 to 2023, and during this time worked closely with Heinz Heinemann, the founding Editor of the journal, and Alexis Bell, his successor. Prof. Somorjai served as a member of the Editorial Advisory Board from 1985 to 2025.