In this study, we described an efficient electrical power generating system containing cyanobacterial photo-H-2 production and custom-built proton exchange membrane fuel cell (PEMFC). The filamentous N-2-fixing cyanobacterium Anabaena cylindrica was used as the photo-H-2 producer. A photosynthesis inhibitor-diuron (DCMU) was used for the enhancement of photo-H-2 production in the culture under argon gas. For the first time, a total of 1.0 mu M DCMU was found to be the most effective treatment, as this produced 3.6 fold higher levels of H-2 in microalgae. By measuring polarization curve, the gas mixture collected from the culture was proven to be an effective fuel for electrical generation through a custom-built PEMFC. When the PEMFC was directly combined with the culture tube, the cells generated as much as 843 mV during a 5-day incubation due to the efficient conversion of solar energy to H-2 by A. cylindrica. Light energy conversion efficiency (LCE) for both solar energy to H-2 and solar energy to electricity were also determined. The LCE for the cyanobacterial conversion of solar energy to H-2 reached a peak at four days with a maximal value of 2.05% and an average value of 1.70% +/- 0.17. The corresponding LCE for the conversion of solar energy to electricity in this system was 1.13% at peak and 0.94% +/- 0.09 on average. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.