The new edition of Principles of Electrochemistry has been considerably extended by a number of new sections, particularly dealing with 'electrochemical material science' (ion and electron conducting polymers, chemically modified electrodes), photoelectrochemistry, stochastic processes, new aspects of ion transfer across biological membranes, biosensors, etc. In view of this extension of the book we asked Dr Ladislav Kavan (the author of the section on non-electrochemical methods in the first edition) to contribute as a co-author discussing many of these topics. On the other hand it has been necessary to become less concerned with some of the 'classical' topics the details of which are of limited importance for the reader