This book is written to serve as an illustrative reference and work book to the Third Semester (APJ Abdul Kalam Technological University, Kerala. 2019 Scheme) on MATHEMATICS-III Partial Differential Equations and Complex Analysis. We provide ample number of worked out examples and a number of exercises for each chapter so as to help the students to understand the subject. The book is written with lot of illustrative examples to develop conceptual understanding, cognitive level learning, and to apply this to specic fields.