The influence of photoluminescence (PL) and trapping on photovoltage (PV) transients has been compared for as-anodized and for oxidized in air por-Si/p-Si structures. Measurements were carried out with time-resolved surface photovoltage and with contact potential difference techniques. Light sources with wavelengths from the infrared to the ultraviolet regions were used for excitation. It was shown that PV based on PL light can be used for the estimation of the PL efficiency. Electron trapping was found to modify the band bending at the por-Si/p-Si interface of the oxidized in air sample. Further it was shown that non-monotonous PV transient features took place on oxidized por-Si/p-Si structures at high levels of optical excitation.