In this work, the simultaneous separation of both organic and inorganic anions and cations was investigated using a mixed bed multi-mode phase namely Scherzo SS-C18. This column consisted of not only C18 ligands, but also anion ligands and cation ligands. It also provides reversed-phase mode, both ion exchange modes and normal phase mode. The HPLC system combined with conductivity detector was used for the separation of seven anions (HCOO^-, NO₂^-, Cl^-, Br^-, NO₃^-, SCN^- and ClO₄^- ) and four cations (Na⁺, K⁺, NH₄⁺ and Cs⁺). The separation conditions were optimized including type of eluent, column temperature, organic modifier and also eluent concentration. Oxalic acid was the optimum mobile phase for the separation of these analytes. The column temperature was studied in the range of 25 - 55 °C, which showed the best result at 50 °C. Moreover, the effect of organic modifier, acetonitrile and concentration of oxalic acid were also optimized. The proposed method was applied to determine these ions in environmental samples.