The paper presents the experimental validation of the "EasyTest Cell" operational principle via comparative electrochemical tests on mEAs carried out in three types of electrochemical hydrogen energy conversion (EHEC) testing cells: conventional polymer electrolyte membrane fuel cells (PEMFC) and polymer electrolyte membrane water electrolyzers (PEMWE), properly equipped with all the required auxiliaries (products conditioning and supplying, reagents removal, etc.), and the simple, autonomous EasyTest Cell. Along with EasyTest Cell validation and demonstration of its advantages, the influence of argon pressure during sputtering on the electrode characteristics, including gas diffusion limitations was investigated. The electrodes under investigation were magnetron sputtered C/Ti/IrO(x) (IrO(x) loading in the range 0.12-0.4 mg cm(-2)), C/Ti/IrO(x)/Pt/IrO(x) (IrO(x) 0.08/Pt 0.06/IrO(x) 0.08 mg cm(-2)), sputtered at various argon pressure C/Ti/Pt (0.15 and 0.25 mg cm(-2)), and commercial ELAT electrode (V.21, Lot # MB030105-1, Pt loading 0.5 mg cm(-2), E-TEK). The results obtained proved the reliability, simplicity (running-periphery-free) and broadened experimental possibilities of EasyTest Cell over PEMFC and PEMWE single cell testing. Thus, significant cost reduction and resource saving in R&D laboratory can be achieved. Moreover, validation of EasyTest Cell contributes not only to testing facilitations, but potentially to standardization of MEA testing since it gives possibilities for precise control and more uniform distribution of the working parameters applied to the testing object, which are both compulsory for performance comparison and qualifying. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.