In this paper, a self-tuning PID controller using just-in-time learning (JITL) technique is proposed. A set of linear models obtained by the JITL provides the information required to adjust the parameters of PID controller. The self-tuning algorithm for the PID parameters is derived by a rigorous analysis based on the Lyapunov method such that the JITL's predicted tracking error converges asymptotically. Simulation results are presented to illustrate the proposed self-tuning PID controller and a comparison with its conventional counterparts is made. (C) 2008 Elsevier Ltd. All rights reserved.