AbstractAccess to the computational Grid is restricted to the laptop and desktop environment since Grid client development has been concentrated in this area. This paper presents the design and implementation of a new, lightweight computational Grid client that provides the same level of functionality and security as its desktop counterparts whilst conforming to the limitations and restrictions of a Personal Digital Assistant environment. A solution has been achieved by taking an architectural perspective of the problem and choosing a tiered, asymmetrical Grid middleware providing an asynchronous messaging model with uniform interface to all resources. The client opens up a new area of Grid computing access: secure and flexible job submission and monitoring to dependable, persistent, powerful and consistent computing services provided by a computational Grid has been freed from static environments into the mobile domain. This has been done without the modification of the underlying Grid middleware and using standards‐based protocols and components: J2ME, X.509 certificates, Secure Socket Layer connections and IEEE 802.11b wireless networking. Copyright © 2006 John Wiley & Sons, Ltd.