Volume 42 follow the pattern of previous issues from Vol. 39 on, which combines review on the latest advancements in photochemistry (every other year on a part of this discipline) and highlights on some topics.

We thank the reviewers, who maintained their thorough work once again, as well as the contributors of highlights. It has been, as usual, quite a tough job to complete all of the contributions (almost) within the planned deadlines. We must admit that, hard work as it may have been, having the opportunity of seeing such a large wealth of photochemical research has been a really nice experience.

We thank the staff of Specialist Periodical Reports at RSC and our colleagues of the Photochemical Group at the University of Pavia, who made photochemistry such an entertaining experience every day.

Angelo Albini and Elisa Fasani