Using the abundance of available electrons generated by immobilized multilayers of the photoactive protein complex Photosystem I (PSI), we have photoreduced platinum particles that are catalytically active for the H-2/H+ redox couple. The resulting platinized PSI films were optimized using electrochemical measurements and then characterized using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and scanning electrochemical microscopy (SECM). These results demonstrate a novel method for generating immobilized platinum catalysts that are readily available on the surface of a photoactive PSI multilayer.