Sensitive, simple, and accurate spectrophotometric methods have been developed for the assay of arrhythmias drug-dronedarone hydrochloride (DND) in bulk drug and pharmaceutical formulations. The proposed method is based on the oxidation reaction of DND with a known excess of cerium(IV) ammonium sulfate (Ce(IV)) as an oxidizing agent in acid medium, followed by the determination of the unreacted oxidant by adding a fixed amount of dye, e.g., amaranth (AM), methylene blue (MB), and indigocarmine (IC), followed by measuring the absorbance at 520, 664, and 610 nm, respectively. The effects of experimental conditions were studied and optimized. The beer's law was obeyed in the concentration ranges of 1.0–10, 1.0–15, and 1.0–8.0 μg mL-1 using AM, MB, and IC dyes, respectively, with a correlation coefficient ≥ 0.9992. The calculated molar absorptivity values are 3.6527 × 104, 3.1212 × 104, and 4 …