We experimentally demonstrate that porous silicon optical microcavities can be effectively used as multi-parametric gas sensors. As known, the photoluminescence intensity and electrical conduction of porous silicon are strongly dependent on environmental properties, such as the dipole moment of molecules of surrounding gases. The sensitivity is large due to the large surface/volume ratio of porous silicon. While these effects can be observed in any porous silicon structure, microcavities of porous silicon allow an additional sensing parameter, i.e. the spectral position of the resonance cavity peak. The position of the peak depends on the index of refraction of the environment, and gives independent additional information. Moreover, we show that the dynamic response of the peak shift is much faster comparing the other sensing parameters. The combined effects on the peak position, luminescence intensity and electrical conduction can allow discrimination between different substances, and therefore porous silicon optical microcavities can work as multi-parametric optical/electrical sensors. We report detection of 1 ppm of NO2 and 500 ppm of ethanol at room temperature. With NO2, the electrical conduction increases and PL quenches, but the peak does not shift, whereas the peak shifts with ethanol (no significant PL quenching is observed at 500 ppm). This suggests that discrimination between different species can be achieved.