The authors report on the fabrication of a pyruvic acid (Pyr)/p-Si heterojunction photodetector and analyses of electro-optical behavior of the device. First, Pyr film was coated on p-Si by spin coating method. The morphology and elemental structure of this film were determined by scanning electron microscopy and energy dispersive x-ray analysis, respectively. In order to analyze the device's performance, the current-voltage (I-V) measurements were performed in the dark. The device was a rectification ratio of about 10(5) in the dark, and photodetector device parameters such as responsivity, on/off ratio and specific detectivity were analyzed in light intensity-dependent I-V measurements. Measurements depending on the light intensity were carried out between 15 and 30 mW cm(-2), at 5 mW cm(-2) intervals. The capacitance-voltage (C-V) and conductance-voltage (G-V) measurements carried out in the dark were analyzed at low and high frequencies in addition to the dielectric properties of the Pyr/p-Si heterojunction. Experimental results showed that the Pyr/p-Si device can be effectively applied to optical sensors and imaging devices.