ISO/IEC 18000-4:2008 is one of a series of International Standards and Technical Reports developed for the identification of items (Item Management) using radio frequency identification (RFID) technology.

ISO/IEC 18000-4:2008 defines the 2,45 GHz protocols that support ISO/IEC 18000-1. Each of the specific physical/data link configurations is defined in a separate sub-clause. The configuration descriptions include a Physical Layer and a Data Link Layer.

ISO/IEC 18000-4:2008 defines the air interface for radio frequency identification (RFID) devices operating in the 2,45 GHz Industrial, Scientific, and Medical (ISM) band used in item management applications. ISO/IEC 18000-4:2008 provides a common technical specification for RFID devices that can be used by ISO committees developing RFID application standards. ISO/IEC 18000-4:2008 is intended to allow for compatibility and to encourage inter-operability of products for the growing RFID market in the international marketplace. ISO/IEC 18000-4:2008 defines the forward and return link parameters for technical attributes including, but not limited to, operating frequency, operating channel accuracy, occupied channel bandwidth, maximum equivalent isotropically radiated power (EIRP), spurious emissions, modulation, duty cycle, data coding, bit rate, bit rate accuracy, bit transmission order, and where appropriate operating channels, frequency hop rate, hop sequence, spreading sequence, and chip rate. ISO/IEC 18000-4:2008 further defines the communications protocol used in the air interface.

ISO/IEC 18000-4:2008 contains two modes. The first is a passive tag operating as an interrogator talks first while the second is a battery assisted tag operating as a tag talks first. The detailed technical differences between the modes are shown in the parameter tables.