In this paper, we present an industrial development of a wireless sensor network technology called OCARI: Optimization of Communication for Ad hoc Reliable Industrial networks. It targets applications in harsh environments such as power plants and warships. OCARI is a wireless-communication technology that supports mesh topology and power-aware ad hoc routing protocol aimed at maximizing the network lifetime. It is based on IEEE 802.15.4 physical layer with deterministic Media Access Control layer for time-constrained communication. During the nontime-constrained communication period, its ad hoc routing strategy uses an energy-aware optimized-link state-routing proactive protocol. An OCARI application layer (APL) is based on ZigBee application support sublayer and APL primitives and profiles to provide maximum compatibility with ZigBee applications. To fully assess this technology, extensive tests are done in industrial facilities at Electricité De France R&D as well as at Direction des Constructions Navales Services. Our objective is then to promote this specification as an open standard of industrial wireless technology.