The electrochemical reduction of CO₂ (CO₂RR) powered with renewable electricity sources provides an alternative to conventional fossil-fuel technologies. Valuable chemicals with a reduced carbon footprint can be obtained from the electrochemical CO₂RR, such as formic acid, carbon monoxide, hydrocarbons, and alcohols.^[1] Formic acid is often highlighted as the most economically viable product for industrial applications in CO₂RR technologies.^[2] The selectivity and activity in the CO₂RR are influenced by several factors, such as the electrocatalyst and electrolyte composition. Tin electrocatalysts are known for their high selectivity towards formic acid/formate. Some advantages of employing Tin-based electrocatalysts include the abundance of Sn and its non-toxicity. On the other hand, to achieve industrial-relevant reaction rates at significant faradaic efficiencies, high overpotentials are often required for CO₂RR on Sn-based catalysts. The influence of the reaction environment, including ion identity, concentration, and pH on the activity and selectivity of CO₂RR has received increasing attention in the last years. However, most recent research focuses on noble metals,^[3] while understanding CO₂RR processes on Sn is still lacking. In this work, we studied how electrolyte conditions impact the selectivity and activity of the electrochemical CO₂RR on metallic Sn. Using a two-compartment electrochemical cell and employing online gas chromatography and liquid chromatography we measured the production of formic acid, carbon monoxide, and hydrogen at different cathodic potentials and electrolyte conditions under mildly acidic conditions (pH 4). At low overpotentials and low electrolyte concentrations, the dominant process is the Hydrogen Evolution Reaction (HER) when production rates for formic acid production are still low. At increasing the negative overpotential, the CO₂RR to formic acid becomes the primary reaction, and the CO and H₂ are minority products. The electrolyte concentration significantly influences the overall CO₂RR activity, particularly in formic acid production, while its impact on the CO rate is lower. The activity towards HCOOH and CO is enhanced with cations’ concentration and size, following their tendency to accumulate near the electrode surface (Li⁺ < K⁺ < Cs⁺). The competing HER is hardly influenced by applied potential, electrolyte concentration, or cation size at pH 4. Additionally, we explored the impact of buffering anions in acting as proton donors by comparing sulfate and bicarbonate solutions. The results showed a drastic increase in HER activity, in high-content bicarbonate solutions in neutral pH, surpassing the activity at pH 4 in sulfate electrolyte. This showcases the crucial role of buffering anions in affecting CO₂RR activity on Sn electrodes by promoting competitive HER. Our study provides insights into Sn's activity and selectivity for CO₂RR in mildly acidic conditions. By optimizing reaction parameters such as applied potential and electrolyte composition, we can steer the reaction towards the desired outcome products, with a specific emphasis on formic acid.