Ultrasonic investigation Studies in Organic Solvent Mixtures were much useful to study the behavior of molecules of the liquids.In this book a novel method of finding reaction rates through ultrasonic velocity measurements is discussed. Another important feature of this book is, Linear Free Energy Relationships are applied and correlated with measured data of ultrasonic velocity and evaluated parameters. Linear Free Energy Relationships such as Kosower, Dimroath, Laidler - Eyring treatments were applied to these measured data and evaluated parameters.It is found to be in agreement. Ultrasonic reaction Studies were carried out through ultrasonic velocity measurements were discussed in this book. Rate constants are evaluated from these measurements. Arrehenious parameters, such as Entholpy, Entropy, Energy of activation, Free Energy of Activation, were evaluated from these measured data and found to be in right order. This book is much useful to the chemical engineers, Physicists and Materials Scientist.