A study of hybrid, enzyme-modified nanoparticles able to produce H-2 using visible light as the energy source has been carried out to establish per-site performance standards for H-2 production catalysts able to operate under ambient conditions. The [NiFeSe]-hydrogenase from Desulfomicrobium baculatum (Db [NiFeSe]-H) is identified as a particularly proficient catalyst. The optimized system consisting of Db [NiFeSe]-H attached to Ru dye-sensitized TiO2, with triethanolamine as a sacrificial electron donor, produces H-2 at a turnover frequency of approximately 50 (mol H-2) s(-1) (mol total hydrogenase)(-1) at pH 7 and 25 degrees C, even under the typical solar irradiation of a northern European sky. The system shows high electrocatalytic stability not only under anaerobic conditions but also after prolonged exposure to air, thus making it sufficiently robust for benchtop applications.