Esomeprazole magnesium trihydrate is an effective proton pump inhibitor used for dyspepsia and peptic ulcer. In the present study and a simple, accurate and precise spectroscopic method has been developed for the estimation of esomeprazole in raw material and tablet dosage forms. The method involves complexation of esomeprazole in H2SO4 with iron(II) and 1,10-Phenanthroline and the colour developed was stabilized by using o-phosphoric acid. The coloured solution showed an absorption maximum of 507 nm. A calibration curve was plotted (0.5-4 μg/ml) and found a regression co efficient r2=0.9723. The limit of detection was found to be 0.522318 and limit of quantification was found to be 0.15833. A result of analysis obtained from the studies was validated statistically and by recovery studies. The methods showed good reproducibility and recovery with %RSD less than 1.