The CuxTi1-xO2 films (x = 0.05, 0.10 and 0.15) with various Cu dopants were prepared by sol-gel spin coating technique on a glass substrate and Si wafer in order to determine their optical and photodiode behaviors. Surface topology of thin films was investigated by Atomic Force Microscopy. The optical properties and dispersion parameters have been calculated completely for the samples by using the single term Sellmeier dispersion relation and Wemple–DiDomenico single oscillator model. Photodiode properties were studied by current-voltage I−V characteristics of Al/n-Si/CuxTi1-xO2/Al at room temperature under various illumination intensities. According to the results, the devices have good rectifying, photoresponse and photodiode properties. The electrical behaviors were characterized also by C−V and G−V measurements for various frequencies. The capacitance–voltage–frequency C−V−f measurements indicate that the capacitance of the devices depends on voltage and frequency. The results confirm that the various Cu doped TiO2 devices are the good candidate for photodiode and photodetector applications.