In this revised edition of our book we retained its concept: The main emp- sis is placed on the fundamental principles of heat and mass transfer and their application to practical problems of process modelling and the apparatus design. Like the ?rst edition, the second edition contains ?ve chapters and several appendices, particularly a compilation of thermophysical property data needed for the solution of problems. Changes are made in those chapters presenting heat and mass transfer correlations based on theoretical results or experimental ?ndings. They were adapted to the most recent state of our knowledge. Some of the worked examples, which should help to deepen the comprehension of the text, were revised or updated as well. The compilation of the thermophysical property data was revised and adapted to the present knowledge. Solving problems is essential for a sound understanding and for relating pr- ciples to real engineering situations. Numerical answers and hints to the solution of problems are given in the ?nal appendix. The new edition also enabled us to correct printing errors and mistakes. In preparing the new edition we were assisted by Jens K¨ orber, who helped us to submit a printable version of the manuscript to the publisher. We owe him sincere thanks. We also appreciate the e?orts of friends and colleagues who provided their good advice with constructive suggestions.