d-Pseudococaine, a diastereoisomer of cocaine, is prepared from l-cocaine by the action of strong base that epimerizes the carbomethoxy group at C-2 to the equatorial position and transesterifies the ester at C-3. The benzoate ester is regenerated by reaction with benzoyl chloride. The d-pseudococaine thus prepared is then subjected to a variety of instrumental and analytical techniques to effect its characterization. The tests done are those commonly used in forensic science laboratories for cocaine analysis. With these data, a laboratory can eliminate or confirm pseudococaine in such an analysis.