Creatine, a small molecule present in muscular tissue of many vertebrates, evolves to one of the most widely used and successful dietary supplements of recent decades (Graham and Hatton, 1999). Importantly, in the industrial manufacturing process, a high quality standard must be maintained. Validated analytical methods capable of providing reliable and consistent analysis of the main substance, side products and potentially harmful impurities must be employed. The principles of those determinations and the nature of possible byproducts will be elucidated in this chapter. In addition, the pure creatine produced may be unstable under certain conditions, e.g. within special formulations or galenical forms. Some hints how to deal with this fact and how to avoid instability will also be discussed. Thus, this chapter will serve as a survey of the paths of chemical synthesis of creatine, its chemistry, properties, stability, analytical determination methods and legal status.