The book includes the basics of physical properties of natural gas necessary to understand natural gas processing and process calculations. Items covered in the first chapter are gas molecular weight, density at operating conditions, heating value, compressibility factor, ..etc. The second chapter covers the basics of phase behavior. The third chapter covers a brief oil and gas separation, where a detailed were presented in the first book (Fundamentals of Oil and Gas Processing). The fourth chapter covers Natural gas hydrates, prediction and inhibition. The fifth chapter covers dehydration of natural gas. The seventh chapter covers natural gas sweetening and sulfur recovery.