This paper is devoted to the preparation of polyaniline/lead dioxide composites (PANI/PbO2) via chemical oxidation of aniline in H2SO4 medium using β-PbO2 as an oxidant. The parameters affecting the polymerization reaction are considered. These parameters are [aniline], amount of β-PbO2, stirring time, and different acids. The prepared composites were characterized by SEM, FT-IR, XRD, TGA, DTA, and elemental analysis. From XRD and FT-IR spectra, it was concluded that high molecular weight polymer could be obtained with high aniline concentration, high amount of β-PbO2, increasing polymerization time and polymerization of ANI at lower temperatures. Thermogravimetric study exhibited that the composite prepared using high amount of β-PbO2 has a higher thermal stability. The application of the composites in the oxidative degradation of Alizarin yellow G and Acid alizarin violet N dyes exhibited good catalytic activity in presence of H2O2 as an oxidant. The reactions followed first-order kinetics and the rate constants were determined.