In recent years, requirements for interoperability, flexibility, and reconfigurability of complex automation industry applications have increased dramatically. The adoption of service-oriented architectures (SOAs) could be a feasible solution to meet these challenges. The IEC 61499 standard defines a set of management commands, which provides the capability of dynamic reconfiguration without affecting normal operation. In this paper, a formal model is proposed for the application of SOAs in the distributed automation domain in order to achieve flexible automation systems. Practical scenarios of applying SOA in industrial automation are discussed. In order to support the SOA IEC 61499 model, a service-based execution environment architecture is proposed. One main characteristic of flexibility-dynamic reconfiguration-is also demonstrated using a case study example.Index Terms-Dynamic reconfiguration, flexibility, function blocks, IEC 61499, IEC 61131-3, industrial automation, interoperability, programmable logic controllers (PLCs), service discovery, service-oriented architecture (SOA), simple object access protocol (SOAP), Web services description language (WSDL).