This paper presents an advanced self-timed Java accelerator core which has extremely low power consumption while providing sufficient performance for even the most demanding real-time telecommunication and multimedia applications. The goal is that the accelerator can be directly attached to any general-purpose processor core running some Java-intensive application software. Asynchronous self-timed circuit technology, where timing is based on local handshakes between circuit blocks instead of a global clock signal, provides a promising platform for obtaining a highly modular low-power Java accelerator implementation.