Recent studies evidence the interplay between the photosensitivity and the gas sensitivity in porphyrin functionalized ZnO nanorods. These effects are critically governed by the transport phenomena of electronic charge across the interfaces of organic and inorganic structures. Therefore, the measurements of energy levels and surface potentials are important to understand the relationship between the effects of light and volatile molecule adsorption. For the scope, Kelvin probe measurements of porphyrin-ZnO structures were performed in dark, under visible light and to organic vapors. Results show a synergic effect of gas sensitivity and photosensitivity for free base porphyrins, while in the case of metalloporphyrins, the coordinated metal ion can alter the cooperation between the two effects, as observed in Zn complex, where the exposure to light increases the adsorption of gases, but the photovoltage is reduced during the exposure to the gas.