New, simple, sensitive, accurate, selective and cost effective method has been developed for the determination sulfa drugs (sulfamethoxazole and sulfamerazine) in bulk and in pharmaceutical dosage forms. The developed method , is a chemical derivatization method involving proton transfer from 2,4,6-trinitrophenol (picric acid) as Lewis acid to the secondary amino group of sulfamethoxazole and sulfamerazine as Lewis base in methanol to form a yellow charge transfer complex exhibiting maximum absorption (λ max) at 420nm and 410nm respectively. The method was linear in the concentration ranges (2-28µg/ml)and(1-30 µg/ml) with correlation coefficient (R2= 0.9992) and (R2=0.9994), to sulfamethoxazole and sulfamerazine sulfa drugs respectively .Intra-day, inter-day precision (as RSD) and accuracy were determined. The results obtained were statistically validated .The method is used to determination sulfa drugs in pharmaceutical preparations.