The paper presents results of research of similar electrical, optical and structural properties of three types of MOS structures prepared on different Si-based semiconductors. Electrical interface properties are investigated by institutionally produced equipment with Charge Version of Deep Level Transient Spectroscopy and time domain C-V. X-ray diffraction at grazing incidence angles is applied to control their structural properties. Optical properties of selected structures are investigated by photoluminescence measurements at liquid helium temperature (approx. 6K in cryostat). Dominant interest is focused on analysis of both electrical properties of MOS porous silicon based structures prepared on p-type crystalline Si and photoluminescence signals of the structures observed around 1.1 eV, respectively. Such parameters as Fermi level position, flat-band voltage, surface potential, position of deep level hole traps, and acceptor density are calculated for various conditions as defined by sample ambient, temperature, and light illumination. Following two main findings are analyzed: i) total suppression of large C-V hysteresis due to suitable illumination and ii) recovering of part of detected interface states in the dark.