FCTESTNET (Fuel Cell Testing and Standardization Network) is an ongoing European network project within framework program 5. It is a three-year project that commenced 2003, with 55 partners from European research centers, universities, and industry, working in the fuel cell field. The main objective of FCTESTNET is to promote the harmonization of testing procedures and methodologies within the European Union. The lack of standardized test methods for fuel cell technology is a fact. The development of standardized test methods is very important for the commercialization of the fuel cell technology. Standardized test methods are one of the most important instruments in the quality management work of any industrial process. The players that have a common interest to promote and develop harmonized test methods for fuel cell technology are: • Standardization bodies (IEC and ISO); • Fuel cell manufacturing industry (type testing and routine testing); • OEMs (acceptance testing); • Research institutes and universities (R&D). The current work presents one of the core results from the FCTESTNET project, namely a proposal of a harmonized testing format for fuel cell technology. The harmonized testing format has been developed based on a testing model that was proposed in the initial phase of FCTESTNET. The testing model describes the common process steps in testing and has been a valuable tool to communicate testing activities and develop test format within the network. The testing model describes testing in general and fuel cell testing in particular. It is a three-step model. The first step is the planning step and comprises the listing of standardized test methods and other references that are required for the execution of any specific testing activity. The second step of the testing model is the testing execution, which is where the actual testing is carried out. The result of the testing execution is here referred to as test output data or test output. The test output is analysed and compared with input data from the planning step and finally reported in the third step, that is the evaluation step. Some examples of specific test inputs, in the context of fuel cell testing, are temperature, vibration, fuel flow, rain, etc. Examples of specific test outputs are current, voltage, gas emissions, heat, degradation, etc. In professional testing, the internal function of the test object is of secondary importance. The object is to be treated as a “black box”. It is the test output and the test result that are of primary importance. Based on terminology originating from the testing model, such as test object, test inputs, test outputs, etc, a harmonized testing format has been developed and proposed. The key terms in the harmonized testing format are test programme and test module. The test programme is defined as a programme comprising two or more test modules. A test module is a test method defined as the variation of one single test input, for example the testing of power output as function of ambient temperature. Furthermore, a test module comprises the objectives, the scope, the test input varied, the test outputs tested, test object class (fuel cell, fuel cell stack or fuel cell system), test procedure, test report, etc.