This Book has primarily been written keeping in view the needs and interest of students of various universities. It has been divided in to two main sections. The first section covers the basic of Flow Injection analysis, different factors effecting on it and their optimizations, the second section consist on application of this technique in development of new methods for determination of a well known pesticide. Some of the salient features of the book amongst many are that it is simple and lucid presentation, comprehensively covers the FIA and provides the systematic treatment of topics, application of this new emerging technique in development of new methods by using spectrophotometer