Malonic acids are dicarboxylic acids which are polar and thus poorly retained in reversed-phase. An Ultra-fast method for separation of homologs of malonic acids on core-shell mixed-mode columns was developed. Column and method can be used for fast isolation of hydrophilic acids in reversed-phase and anion-exchange modes. Base-line separation with a perfect shape is achieved for all compounds. No ion-pairing reagent is involved.