The longitudinal photo detectors are widely used in different devices of optoelectronics as the detectors of azimuth shift of the light source, semiconductive layers of the IR-image converters and other position-sensitive devices. The longitudinal type photodetectors considered in the present work are prepared on a base of CdSe thin layers obtained by the chemical deposition from aqueous solutions. At the first electrode, the In2O3 layer was preliminarily deposited onto glass substrates. For activation of samples, a thermal deposition of copper followed by annealing in vacuum was used at temperatures of 350-450 degree(s)C for 5-30 min. Investigation of dark and light conductivity, the spectrum and kinetics of photoconductivity of CdSe films have been carried out. The studies of the current-voltage characteristics of In2O3- CdSe have been performed based on the generalized approximate theory of injection contact phenomena in semiconductors. The volume (no) and precontact (nc) change carrier concentration, recombination (Nrec) trapping (Ncn) center concentration, the absorption edge and the transmission coefficient, the region and minority carriers have been determined. The dark I-U characteristic is sublinear, while the light I- U characteristic is superlinear that causes the increase of multiplicity coefficient, K, at elevated voltages. The absorption spectrum and the PC spectrum of the CdSe annealed samples and also of Cu-doped samples. CdSe:Cu have been investigated. The existence of uniform surface and the phase transition play an essential role in the formation of optical spectra. The absorption edge for the annealed samples corresponds to cubic modification and in the transmission range a wide diffuse band imposed on the fundamental edge of a single crystalline CdSe is observed. The CdSe films obtained by chemical deposition method are characterized by high reproducibility, sensitivity in the wavelength region of (lambda) =(0.54-0.6)micrometers , electric strength (106 V/cm), high-resistivity ((rho) approximately 109-1010 Ohm. Cm). Optical transmission (more than 60%).