Flexible electronic is becoming an important research field relative to the number of applications emergence like flexible displays [3], networks of solar cells [4,5], tags for identification by RFID [7, 8], flexible batteries [7,8], electronic circuits for clothing [9,10], and biomedical devices [11-13]. These different devices are mostly designed and fabricated on plastics substrate (PET, PEN, and polyimide) and sometime on paper-based substrate. The paper is one most ubiquitous product in modern society by his use for disposable cups, packaging product, books and newspaper etc. For these different advantages and its properties of foldability, ease of operation (can be cut of perforated for easing tearing), biodegradability and recyclability, the paper is a material of choice for electronic component substrate. Our laboratory works since many years on implementation of microelectronics process on paper substrate [14-16]. In pursuit of this goal, aluminum anodization process had been demonstrated on paper for gas sensor fabrication. It is well known that porous Anodic Aluminum Oxide (AAO) is one of the porous ceramics which is widely used for sensors and template synthesis in electronics. The main sensing applications of porous AAO are to detect humidity, ammonia, hydrogen, nitroaromatics, and optical electro/chemo biosensors by functionalizing various biomolecules. [16-20] This article focused on porous anodic aluminum oxide enhancement on paper by anodizing aluminum layer deposited by thermal evaporation. This aluminum layer has been anodized in 15 wt % phosphoric acid at temperature maintained between 8-10 °C. The anodization process had been explored by changing the voltage applied and the time of anodization to obtain the best sensitive layer for ammonia gas. On the AAO layer formed as show on figure 1, an interdigital capacitance has been fabricated. Different measurements were performed for measuring ammonia variation (7ppm to 300ppm). The results are shown on figure 2. The different surface morphology found in comparison to capacitance measurements have allowed to discuss about sensor behavior overlooked of porous AAO thin film layer on paper substrate.