• Carbonic acid tablets containing citric acid and sodium bicarbonate were designed. • Carbonic acid tablets elicited submandibular-sublingual salivary secretion. • Carbonic acid tablets had less effect on parotid salivary secretion. • CO 2 produced from the carbonic acid tablets stimulated the gustatory-salivary reflex. Carbonic acid tablets containing citric acid and sodium bicarbonate were designed to dissolve in aqueous solution, and release carbon dioxide (CO 2 ). The effect of the carbonic acid tablets on salivary secretion was examined in humans. Healthy male volunteers participated in the whole salivary flow secretion (n = 6) and submandibular-sublingual (SMSL) gland and parotid gland salivary flow secretion (n = 12) studies. Placement of a carbonic acid tablet on the apex of the tongue increased the whole saliva volume. The carbonic acid tablets promoted SMSL salivary secretion, but had less effect on parotid salivary secretion. A citric acid tablet, an acidic tastant, promoted both SMSL and parotid salivary secretion. A tablet containing only sodium bicarbonate, a component of the carbonic acid tablet, had no effect on SMSL salivary secretion. In conclusion, a carbonic acid stimulus specifically enhances salivary secretion from SMSL glands via the formation of CO 2 .