It is well-known that the electrolytes can influence the electrochemical reduction of carbon dioxide (ERCO2) in aqueous media. In this work, we explore the effects of alkali metal cations and anions (Li+, Na+, K+, Rb+, Cs+ HCO3-, Cl-, Br-, I-) on the current density and product selectivity for the ERCO2 into formic acid (HCOOH) on the SnO2/carbon paper (SnO2/C) electrode. Results of the ERCO2 experiments show that for the cations, the promotion effects on current density and faradaic efficiencies (FEs) are in the order of Li+ < Na+ < K+ < Cs+ < Rb+. For the anions, the current density values are in the order of NaHCO3 < NaCl NaBr < Nal and KHCO3 < KCl approximate to KI < KBr, respectively, and that on the FEs for the formation of the HCOOH (FEHCOOH) is HCO3-< on this result, the effects of alkali metal cations and anions on ERCO2 are discussed. (C) 2020 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.