A recent study demonstrated the impact of citric acid on salty taste in humans. We examined the opposite effect: the impact of NaCl on sour taste at low concentrations of both tastes (i.e., lower dilutions among those specified in the PN-ISO 3972:2016-07 standard). Volunteers were presented with the samples of pure solutions of citric acid (SOUR) and taste mixtures of SOUR and NaCl in different concentrations. They were asked to identify taste and its intensity. Our results showed that low doses of NaCl (analyzed collectively, but mainly the concentrations of 0.16 and 0.24 g/L, and to a much lesser extent 0.34 and 0.48 g/L) improved the recognition of sour taste in a SOUR(0.25 g/L)-NaCl mixture compared to a pure SOUR solution (0.25 g/L). NaCl's enhancing effect on sour taste intensity was visible in some cases but not in all. The results suggest that NaCl has the potential to improve the recognition of sour taste under certain conditions. Further studies are required to fully understand the mechanisms of sour-salty interaction in the context of sour taste, and how these mechanisms depend on the substance's concentration.