New multimetallic catalysts immobilized on different carbon supports have been developed to be used as anodes in direct alcohol fuel cells (DAFC). The performance of a new catalyst is evaluated by classic electrochemical measurements, which are performed in extremely clean systems, in an inert atmosphere, using pure reactants and usually in a stationary configuration. However, real DAFCs might operate in the presence of impurities, in 02-containing fuel and under hydrodynamic conditidns, where the fuel continuously feeds the anode. Here, we propose a new flow system for measuring the electroactivity of nanoparticles (FSMEN). We take advantage of a flow injection system integrated with a screen-printed electrode cell to develop our method. In FSMEN, the fuel solution is continuously carried directly to the screen-printed electrode modified with candidate nanoparticles (NPs) to be used as anode of DAFC. During the injection, anodic current is generated when the fuel reaches the surface of the catalysts under a potential suitable for the electrooxidation reaction. We used FSMEN to investigate the activity of Pt NPs immobilized on carbon, multi-walled carbon nanotubes and graphene nanoribbons towards methanol electrooxidation, in comparison to classic measurements. Our method is robust, reproducible and provides new information due to the hydrodynamic current output and the use of an opened system, which is closer to a real fuel cell scenario. (C) 2017 Elsevier B.V. All rights reserved.