Photosystem I (PSI) is a nanoscale protein complex that governs many of the primary events of photosynthesis, the key biological process that converts sunlight into chemical energy. Because of its nanoscale size and photovoltaic properties, PSI offers great potential for use in molecularly engineered energy conversion devices upon extracting it from plants and assembling it at surfaces. The research described in this presentation focuses on the integration of spinach-extracted PSI at electrode surfaces, formed by self-assembled monolayers (SAMs) on gold. Covalent immobilization offers significant enhancement over physical and electrostatic immobilization methods. We demonstrate that covalently bound PSI produces up to a ten fold increase in photo-induced current and is more stably attached to the surface. The ultimate goal of this research is to develop a photoelectrochemical device in which PSI converts solar energy into useful electrical energy.