The Twelve Keys of Basil Valentine is a widely reproduced alchemical book attributed to Basil Valentine. It was first published in 1599 by Johann Thölde who is likely the book's true author. It is presented as a sequence of alchemical operations encoded allegorically in words, to which images have been added. The first Basil Valentine book to discuss the keys is Ein kurtz summarischer Tractat, von dem grossen Stein der Uralten ("A Short Summary Tract: Of the great stone of the ancients"), 1599.

The first part of the book is a discussion of general alchemical principles and advice about the philosopher's stone. The second half of Ein kurtz summarischer Tractat, under the subtitle "The Twelve Keys", contains twelve short chapters. Each chapter, or "key", is an allegorical description of one step in the process by which the philosopher's stone may be created. With each step, the symbolic names (Deckname, or code name) used to indicate the critical ingredients are changed, just as the ingredients themselves are transformed. The keys are written in such a fashion as to conceal as well as to illuminate: only a knowledgeable listener or alchemical adept was expected to correctly interpret the veiled language of the allegorical text.