SLC4A11, a member of the Solute Linked Cotransporter 4 family that is comprised predominantly of bicarbonate transporters, was described as an electrogenic 2Na⁺/ B(OH)₄^- (Borate) cotransporter and a Na⁺/ 2OH^- cotransporter. The goal of the current study was to confirm and/or clarify the function of SLC4A11. In HEK293 cells transfected with SLC4A11 we tested if SLC4A11 is a: 1) Na⁺:HCO₃^- cotransporter, 2) Na⁺:OH^- (H⁺) transporter, and/or 3) Na⁺:B(OH)₄^- cotransporter. CO₂/HCO₃^-perfusion yielded no significant differences in rate or extent of pHi changes or Na⁺ flux in SLC4A11-transfected compared to control cells. Similarly, in CO₂/HCO₃^-, acidification on removal of Na⁺ and alkalinization on Na⁺ add-back were not significantly different between control and transfected indicating that SLC4A11 does not have Na⁺:HCO₃^- cotransport activity. In the absence of CO₂/HCO₃^-, SLC4A11-transfected cells showed higher resting [Na⁺_i] (25 vs 17 mM), increased NH₄⁺ induced acidification and increased acid recovery rate (160%) after an NH₄ pulse. Na⁺ efflux and influx were faster (80%) following Na⁺ removal and add-back, respectively indicative of Na⁺:OH^- (H⁺) transport by SLC4A11. The increased alkalinization recovery was confirmed in NHE-deficient PS120 cells demonstrating that SLC4A11 is a bonafide Na⁺:OH^- (H⁺) transporter and not an activator of NHEs. SLC4A11 mediated H⁺ efflux is inhibited by EIPA (EC50: 0.1 µM). The presence of 10 mM borate did not alter dpH_i/dt or pH during a Na⁺-free pulse in SLC4A11-transfected cells. In summary our results show that SLC4A11 is not a bicarbonate or borate-linked transporter, but has significant EIPA-sensitive Na⁺: OH^- (H⁺) and NH₄⁺ permeability.