In the field of polymer electrolyte membrane water electrolysis (PEMWE), a significant amount of excellent scientific results has been generated during the past decades. However, the comparability and reproducibility of these results between different cell types and different laboratories is not always straightforward. In this contribution, an exemplary ring experiment on the single-cell level compares the performances of three cell types: the differential cell () and two integral cells: an elongated cell () and a circular cell (). Therefore bi- and trilateral experiments were carried out with differently prepared catalyst-coated membranes (CCMs) and porous transport layers (PTLs) as well as with an alternative catalyst-coated electrode (CCE) concept in three laboratories. This contribution aims to evaluate the grade of systemic inequality, which still permits a comparison of individual parameters. The comparison of CCM preparation methods showed no significant influence on the initial electrochemical characteristics. An HCl etching of the anode PTLs in two different cells confirmed to be a useful treatment for the reduction of Ohmic losses in PEMWE cells. Self-made CCEs could not serve as an alternative concept, owing to their inadequate contact between the electrode and the membrane, which was observed in three laboratories as well. The general compatibility between the different cells was proven by the observation of a phenomenon in one laboratory that could be reproduced in one or two other laboratories. In this context, the size and geometry of the single cells did not influence the performance, indicating that up to the present measuring range and with sufficient water feed rates, the different single cells were functioning comparably. [GRAPHICS] .