Since the first publication of the book, a surge of interest in physicochemical hydrodynamics (PCH) has produced a flurry of advances in the field, as researchers became aware of the subject’s practical applications across numerous disciplines. The Second Edition of Ronald F. Probstein’s Physicochemical Hydrodynamics is significantly expanded and revised to provide increased coverage of the field. All of the material was supplemented with problems for students, and a solutions manual is available for instructors. The continued demand for the book necessitates that the Second Edition be reprinted in paperback so that it may be more widely available to students and practitioners. This highly respected book emphasizes rational theory and its consequences to demonstrate the underlying unity of PCH, which allows diverse phenomena to be described in physically and mathematically similar ways. Physicochemical Hydrodynamics communicates the fundamentals while, at the same time, conveying the importance of applications of PCH to a variety of fields, including: mechanical, chemical, and environmental engineering; materials science, biotechnology, microfluidics, and fluid aspects of nanotechnology. Numerous illustrations, analogies, and examples highlight the text and help to clarify and solidify students’ and professionals’ understanding of the material.