The paper describes the synthesis and characterization of polyaniline (PANI)/CrO3 composites. Samples of PANI/CrO3 composites were synthesized by chemical oxidative polymerization of aniline added with various weight % of CrO3 in the presence of ammonium persulphate as an oxidant. The samples were characterized by Fourier Transform Infrared (FTIR) Spectroscopy, Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and their thermal and electrical properties have also been investigated. The results of FTIR and SEM techniques confirm the presence of CrO3 in the composites. The FTIR spectra show that the intensity of characteristic peak of metal oxide increases and also there exist small shifting in the frequencies of characteristic bands of PANI in the composite. In the SEM micrograph of PANI/CrO3 composites, the smaller size particles are observed as compared to PANI. It reveals that CrO3 particles are embedded in the PANI structure. From Thermo Gravimetric Analysis (TGA), it is concluded that the thermal stability of PANI is more in composite form. First, it increases with increase in CrO3 content up to 10 weight% and thereafter it starts decreasing. The DC electrical conductivity also shows similar kind of behavior. DC conductivity of PANI as well as PANI/CrO3 composites increases with increase in temperature. Due to higher value of conductivity and thermal stability as compared to PANI, these composites can act as good conducting materials at higher temperatures. The composite can also act as a promising material for high performance humidity sensors.