A straightforward and sensitive spectrophotometric method for the determination of Dapsone has been developed. The method is based on the charge transfer complex formation reaction of dapsone as n-donors with o-chloranil (o-CA) as π-acceptor in aqueous medium forming coloured complex with maximum absorption at 394 nm. Beer's law was obeyed in concentration ranges of 0.125-1.25 µg/ml with molar absorptivity 1.092×105 L. mol-1.cm-1. The accuracy of the method (average recovery %) was 100.34% and precision (RSD) ≤ 3.91 %. The results show that complex is formed in ratio 1:2 with the stability constant 3.81×109 l2.mol-2. The suggested method was applied successfully to determine Dapsone in its pharmaceutical preparation.