<p>Measuring the performance of single cell proton exchange membrane fuel cells (PEMFC) is routine for laboratories assessing the impact of new materials and operating conditions on these devices. Though there are standardised test methods, there has not been a published method to assess the uncertainty on the results of such measurements. This makes it challenging to assess the reliability of conclusions drawn from data and to make meaningful comparisons of measurements made at different laboratories, even when these are made following the same standards.</p><p>This paper estimates the uncertainty on single cell PEMFC performance measurements made at standard operating conditions, considering both the scatter in identical repeat measurements and the impact of control and measurement uncertainties on the operating conditions. The results of the analysis on an example cell show that the uncertainty on the air flow rate and cathode pressure are the largest contributors to an overall expanded measurement uncertainty of 32 mV at 1&#xa0;A cm^− 2. The method and analysis outlined here have been designed to be quick and simple to implement at other laboratories for a better understanding of measurement reproducibility and the biggest contribution to variations in measurements.</p> Graphical abstract <p></p>