As part of the European contribution to the Russian segment of the International Space Station (ISS), the European Robotic Arm (ERA) is designed under contract of the European Space Agency by Fokker Space as the Prime contractor. The particularly challenging aspect of the ERA thermal design is to enable ERA operation under all possible in-orbit thermal environmental conditions which are to be experienced throughout its 10 year life. These conditions can be between extreme cold without sunlight for hibernation to extreme hot with ERA operating in full sunlight in close vicinity to a large station item, for instance, the solar arrays.First a short description of the ERA system is given with a summary of the main thermal design features. The system level thermal balance test on the ERA Engineering Qualification Model (EQM) is intended to validate the system level thermal model, which consists of the subsystem thermal models as supplied by the respective subcontractors. In addition the thermal models of the Limbs and the Joints were validated during this test.The ERA EQM TB test has been performed at the Large Space Simulator (LSS) facilities at ESTEC in Noordwijk, the Netherlands and took about 12 days pure testing.The configuration of the test item together with the thermal adapter used in the LSS are discussed.The thermal balance test consisted of the following phases: a hot operational test phase in which the maximum temperature levels in a hot thermal environment are obtained, a cool down phase that verifies the time-dependent thermal behaviour of the system, a cold hibernation phase showing the operation of the active thermal control system followed by a steady state with suppressing of thermostat switching. a gradient test case with solar simulation where one side of ERA is illuminated and the other is exposed to a cold environment, intended to verify internal gradients. The test item was equipped with ∼370 thermocouples to monitor the internal and external temperatures.The test itself and the subsequent thermal model correlation activities are discussed. Conclusions and recommendations for the conducting of this type of test are highlighted.