Porous structure of silicon was fabricated successfully by anodization in an electrolyte containing aqueous hydrofluoric acid and ethyl alcohol. Nano TiO2 powder was prepared by sol-gel method and calcinated at different temperatures viz; 300 degrees C, 400 degrees C, 500 degrees C and 600 degrees C. The structural studies revealed that, the cubic structure of the crystalline silicon was retained even after becoming porous. However, TiO2 shows phase transformation from anatase to rutile as calcinated temperature increases. The photo catalytic activity of immobilized nano-TiO2 on porous silicon was investigated by the degradation of methylene blue (MB). The porous silicon layer shows significant improvement in photo catalytic activity of TiO2 powder. The role of biasing of the silicon substrate on the extent of degradation was investigated and it was found that the negative bias shows enhancement in photodegradation. (C) 2014 Elsevier Ltd. All rights reserved.