A simple, sensitive spectrophotometric method was developed for the determination of rabeprazole sodium (RA) in pure form and for pharmaceutical formulations. The charge transfer interaction between RA and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) as an acceptor was investigated spectrophotometrically. Variables affecting the reaction were studied and optimized. The proposed method was applied successfully to the determination of RA in its pure form and pharmaceutical dosage forms with good accuracy and precision. The formation of charge transfer complex and the site of interaction was confirmed by using UV-Visible spectrophotometry, FT-IR spectrometry, and 1 H NMR techniques. Based on Job's method of continuous variation plots, the obtained results indicate the formation of 1:1 charge transfer complex with a general formula [(RA) (DDQ)]. Statistical comparison of the results with the reference method shows excellent agreement and indicates no significant differences in accuracy or precision.