几乎不溶于水，溶于乙醇。乙醇溶液经长时间保存后，可因羧基起酯化作用而使灵敏度显著降低。原生动物活体染色，酸碱指示剂 (pH 4.4 to 6.2) ，临床血清蛋白生化检验。pH变色范围4.4(红)-6.2(黄)。滴定氨、弱有机碱和生物碱，但不适用于除草酸和苦味酸以外的有机酸。可与溴甲酚绿和亚甲基蓝组成混合指示剂以缩短变色域和提高变色的敏锐性。沉淀滴定的吸附指示剂，如用硝酸钍滴定氟离子。检定游离氯、亚氯酸盐等氧化剂。 Methyl red (MR) is an anionic azo dye. It changes from red to yellow when pH of aqueous solution is altered from 4.4 to 6.2. pKa of the indicator is 4.80. MR was used to study its degradation using Fenton′s reagent