The anterior stomach of larval Aedes aegypti is an alkalinizing organ where basolateral V‐ATPase drives luminal alkalinization to a pH of up to 12. However, the apical mechanisms involved are unknown. We hypothesized that luminal alkalinization involves absorption of H+ via apical H+ channels. Such a system would require increased intracellular pH (pHi) to function effectively. pHi was monitored using live cell imaging and BCECF as a pH‐dependent fluorophore. Serotonin (0.2 ìM), which stimulates luminal alkalinization, increased pHi in the anterior stomach from 7.0 ± 0.1 to 7.7 ± 0.1 (N = 64), whereas pHi was not affected in the posterior stomach (6.7 ± 0.1 before and 6.8 ± 0.1 after serotonin; N = 19). Perfusing the lumen with pH 10 saline increased pHi to 8.6 ± 0.1 (N = 41), suggesting a marked apical H+ permeability. However, in presence of luminal Zn2+ (10 ìM) similarly high pHi values were recorded (8.2 ± 0.1; N = 15), indicating that an apical proton channel, if present at all, cannot be blocked with Zn2+. The rate of pH change after switching to pH 10 in the lumen in the presence or absence of luminal Zn2+ was also not different. Together these results show that remarkably alkaline pHi values can be observed in the anterior stomach of larval Aedes aegypti. However, further investigation is required to determine the transporters involved in this unique physiological system. This work was supported by NIH (1R01AI063463‐01A2).