We examined the C-13/C-12 and O-18/O-16 stable isotope ratios (delta C-13, delta O-18) of ascorbic acid from acerola and of synthetic origin. Although the obtained delta C-13 values were partially overlapping for the two species, delta O-18 values were higher for ascorbic acid from acerola, than values obtained for synthetic ascorbic acid. From this study, it was demonstrated that carbon and oxygen isotopic composition analysis can discriminate ascorbic acid from acerola from that of synthetic origin.