Abstract The theory of timed Communicating Sequential Processes is a mathematical approach to the design and analysis of timed distributed systems. This paper extends the language of timed CSP to include a general treatment of recursion. A semantics for mutual recursion is introduced, together with a sufficient condition for the necessary fixpoint to be unique. The resulting language has the familiar unwinding property of process algebra, and exhibits a number of useful algebraic identities. A theory of recursion induction is formulated, and a simple example is presented to illustrate its use.