In this work, we report on the successful assembly of cyanobacterial photosystem I (PSI) on carbon nanotubes for light-to-current conversion applications. For this purpose, glassy carbon electrodes (GCE) have been modified with multi-walled carbon nanotubes (MWCNTs). The surface of the MWCNTs has been adjusted in a non-invasive way by the use of a carboxylated pyrene derivative to achieve a covalent fixation of PSI. Our results show a cathodic photocurrent response and functionality of the biohybrid electrode upon illumination. The experiments verify that the photocurrent generation can clearly be attributed to a functional PSI on the electrode interface. An additional implementation of cytochrome c (cyt c) into this electrode architecture results in a 25fold enhancement of cathodic photocurrent response (0.8 to 18 mA cm À2 at À100 mV and 100 mW cm À2 ), which can be attributed to an improved connection of PSI with the underlying electrode.