The purpose of this paper is to present an automation architecture based on intelligent agents. Starting from the functional requirements of a process automation system, a hierarchical automation architecture is formulated in order to down intelligence to inferior levels. This advantage is possible grace to multi-agent systems, which allow the implementation of interoperativity, heterogeneity and complexity due to the requirements of industrial automation. The architecture is composed by a superior layer, and a middleware layer. The superior layer is constituted by two multi-agent systems, which are based on the control and automation functionalities. The middleware layer is designed in order to support superior layer activities and manages the communications from/to field devices. This layer satisfies the FIPA specifications, it also contains two subsystems: one to handle the communications among different sites, and other to give management services of agents. The middleware can support any multiagent system, and has great design versatility.