The development of co polyimide's is one of the biggest achievements made in chemistry which has a significant effect on everyday life. Remarkable improvement in humanity's progress has been observed from the " Stone era" to the "Iron era" to the "Bronze era" to the "polymer era". "Polymer" is now a household word. The aim of this book is to provide a brief knowledge about co-polyimides. We have included the synthesis of novel compounds and their characterization by various spectroscopic techniques.