Mass Transfer complements the third edition of Heat Transfer by A.F. Mills and C.F.M. Coimbra (Temporal Publishing, 2016). It is a revised, updated and expanded version of the 2nd edition of Mass Transfer by A.F. Mills (Prentice-Hall, 2001). Contents are divided into 3 chapters: Elementary Mass Transfer (low-mass transfer diffusion and convection), Advanced Mass Transfer (high-mass transfer diffusion and convection), and Mass Exchangers (single-, two-stream mass exchangers, filters, catalytic reactors, electrostatic precipitators, fibrous filters, cooling towers, etc.). New materials added to the third edition include: a new section (2.8) on the phenomenon of diffusion creep (slip) in gas mixtures, including isobaric diffusion, equimolar counterdiffusion, and diffusion creep in Stefan flows; updated materials on three-way catalytic reactors to reflect technology developments in recent years; and additional exercises. This book is a suitable text for a one-quarter/semester graduate-level course on mass transfer for mechanical, aerospace, chemical or nuclear engineers. By omitting the more advanced contents on mass exchangers in Ch. 3, this book is also suitable for a senior-level undergraduate course in a variety of engineering programs.