Polyaniline- (PANI) praseodymium Oxide (Pr2O3) composites have been synthesized by in situ polymerization method with different weight percentages. The synthesized composites have been characterized by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. The temperature dependent conductivity shows that the conductivity is due to the hopping of polarons and bipolarons. These composites show negative thermal coefficient (α) behavior as a function of temperature, which is characteristic behavior of semiconducting materials. Sensor studies have been carried out by two-probe method and found that the sensitivity increases with increase in % RH. It is noticed that stability increase is due to the presence of Pr2O3 in polyaniline up to 30？wt%. A fast recovery and response time along with high sensitivity make these composites suitable for humidity sensors. 1. Introduction Conducting polymer has achieved more attention towards the humidity sensing application in present era due to its low weight, easy processing, and high absorption capability because of its porous nature [1]. Among the large variety of conducting polymers, polyaniline (PANI) has emerged as the most promising one because of its diverse properties like relatively inexpensive monomer, easy preparation, high yield of polymerization, environmental stability, and unique processability for device fabrication [2, 3]. The various techniques such as electrochemical polymerization, chemical oxidation, and electrochemical deposition and spin coating have been explored for the fabrication of polymer sensors [4]. Advantages with polymers as sensing materials are light weight, flexible, low cost, and simple fabrication process. Polyaniline has shown very promising results for sensing applications in comparison to other classical sensor materials employed in the fabrication of sensors [5, 6]. Various oxide doped polymer composite materials have been examined as the humidity sensor; for example, ZnO, CdO, and WO3 are reported to exhibit high sensitivity toward humidity [7, 8]. However, further improvements in the performance of the mixed-potential type polymer sensors are still needed in order to realize a commercially viable device of this type [9]. Basically, polymer metal oxide is used in humidity sensor applications and is prepared by conventional and advanced wet chemical processing methods at room temperature and is mainly developed to offer porous bodies. The advantage of an absorbent spongiform surface rather than a condensate is a greater permeability of water
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