Twenty-six quinoline-2,4-dicarboxylic acids (QDC's) were synthesized by a modified Doebner-von Miller pathway and tested as inhibitors against the glutamate vesicular transport (GVT) protein. The QDC's were active as inhibitors with the most potent QDC's found to contain halogens at the 6-/8-position, a hydroxyl at the 8-position, or a tethered aromatic moiety at the 6- or 7-position of the quinoline.