Crucial sensor parameters like sensitivity, response time and recovery time at low ppm were studied and analysed by photoluminescence (PL) quenching technique. A comparison was drawn from various porous silicon samples prepared under different electrochemical anodization conditions. Porosity dependent sensing results were analysed and it was observed that samples turned more sensitive with an increase in porosity. Samples were tested in the presence of linear aliphatic alcohols (methanol to n-octanol) and water in the range of 10100 ppm. Trifling response was shown for water, while a discernible change in sensitivity was observed when samples were tested with alcohols. The morphological changes in porous structure and the chemical nature of organic adsorbates were ascertained to be the primary reasons for sensing by porous silicon. © 2011 World Scientific Publishing Company.