This paper presents the selective and highly sensitive performance of porous TiO2/nano-Si heterostructure for ethanol sensing. The fabrication steps involved were scalable and reproducible making the device eligible for batch fabrication suitable for industry production. The sensor response was recorded as a change in resistance upon exposure to a variety of organic vapors in the concentration range of 5-500 ppm and in simulated real breath conditions. Although the response was obtained at room temperature, however, the operating temperature of the sensor was found to be around 100 °C. The sensing mechanism has been explained on the basis of adsorption-desorption theory of gases, physical, and chemical properties of the materials. A prototype was built for complete realization of the sensor. The sensor data from the sensor array comprising of hetersostructure and its single-layer counterparts were collated and signal conditioning like Regression model and PCA was done. These were used for assessing the alcohol concentration and separation of analytes for the development of E-nose system. © 1963-2012 IEEE.