The present text book entitled ?Physicochemical Principle in Pharmaceutics? deals with the physical and chemical properties of the drugs and recipients which must be understood thoroughly in order to put it into a suitable dosage form. It also includes the stability of the drug product, its Solubility, Dissolution, Diffusion, Kinetics, Complexation and Protein binding. Polymer?s, Polymer's particularly those of high molecular weight are used in the development of new devices that deliver drugs to the body at preprogrammed rates and these have been included in the present book. Theology, Micromeritics, Thermodynamics, States of matter, Surface active agents. Interfacial Phenomenon, Colloids, Suspension and Emulsion have also been included. This book is divided into fourteen chapters and we have envisaged to include not only the recently change semester wise syllabus of Physical Pharmacy for undergraduate students of Rashtrasant Tukdoji Maharaj Nagpur University but also the syllabus of Physical Pharmacy of all the prominent universities of India. Each chapter is explained with diagrams and graphical illustrations wherever necessary, with special emphasis on application in pharmacy and medicine. It is worthy to note that equation when properly described are very effective in representing physicochemical theories and these have been included in the text along with solved and unsolved problems for better understanding of the subject. This book will be very useful to undergraduate and postgraduate students of pharmacy courses and also to Ph.D. research scholars. This book, in the chapter of interfacial phenomenon, also includes in detail the literature survey, theory, measurements and applications of Zeta potential in Pharmacy and Medicine which will be very useful to research scholars, interested in this facinating subject. Contents - 1. States and Properties of Matter 2. Solubility and Distribution Phenomenon 3. Diffusion and Dissolution 4. Kinetics and drug Stability 5. Complexation 6. Surface Active Agents 7. Interfacial Phenomenon 8. Micromeritics 9. Rheology 10. Colloidal Dispersions 11. Suspension 12. Emulsion 13. Thermodynamics 14. Polymer Science Bibliography