An understanding of the phenomena associated with the deoxidation of steel is of vital importance for the production of clean steel.Till recently, deoxidation studies and control were handicapped by the lack of a suitable method for the rapid and accurate determination of the oxygen activity in liquid steel. The advent of the solid electrolyte has provided a breakthrough in this direction. In the present work, a solid electrolyte based oxygen sensor was developed and used for the study of thermodynamics and kinetics of deoxidation of steel in a 15 kg induction furnace. Subsequently, an industrial sensor was also developed and successfully tested in a LD convertor in a steel plant. The present book depicts on direct measurment of oxygen activity , various aspects of deoxidation and morphology of non metallic inclusions with silicon, calcium silicon alloy and aluminium in liquid steel. It is a promising book for oxygen sensor development in liquid steel in a laboratory and commercial applications. The book is very much useful for students for research and industrial sectors for all processes of steel making.This book,therefore,is a success story for deoxidation of Steel.