Heat denaturation studies of desoxyribonucleic acid in sodium chloride and tetramethylammonium chloride solutions of low ionic strength have shown that DNA melts at a lower temperature in the TMACl solutions. Electrophoresis experiments with DNA in a low ionic strength TMACl medium have disclosed that DNA has only a slightly higher mobility in 0.01 F TMACl than in 0.01 F NaCl.