In this article, we attempt to shed light on Baudelaire's poetic alchemy in his masterpiece Les Fleurs du mal, and also on the technique by which this poet-chemist succeeds in transforming the science of alchemy into an aesthetic phenomenon that has remained immortal for centuries. First of all, alchemy, now known as chemistry, is a technico-practical science that revolves around the transformation of base elements into noble metals. Later, this science successfully entered other fields of knowledge such as astronomy, philosophy, literature and even medicine, thanks to its theoretical-mystical nature. Nevertheless, alchemy assumes that mediocre materials, such as iron, are originally expensive elements, like gold, but they need to be transformed several times in order to achieve nobility. The author of Les Fleurs was undoubtedly among the first to consider this alchemical process as a new resource for inspiration, and as a very fertile field from which to profit in the course of his literary productions.