A Spectrophotometric method for the determination of pentoprazole sodium in bulk and pharmaceutical formulations was developed by the authors. The method is based on the color reaction between the sample solution of the drug and a solution of aluminiumeriochrome cyanin R. the reagent was found to be unique and novel in the detection and determination of the drug. A reddish purple color solution is the resultant of the reaction between the drug and the reagent. This reddish purple colored product showed λ max at 533.5nm. Beer's law was found to be obeyed in the concentration range 3.2-12.8 µg ml -1 . Limit of detection was found to be 0.048 µg ml -1 and limit of quantification was 0.148 µg ml -1. The method was found to be sensitive, simple, easy, accurate and precise.