Provided herein are improved fluorogenic compounds and probes that can be used as reagents for measuring, detecting and/or screening hypochlorous acid or hydroxyl radical. The fluorogenic compounds of the invention can produce fluorescence colors, such as green, yellow, red, or far-red. Also provided herein are fluorogenic compounds for selectively staining hypochlorous acid or hydroxyl radical in the mitochondria of living cells. Provided also herein are methods that can be used to measure, directly or indirectly, the presence and/or amount of hypochlorous acid or hydroxyl radical in chemical samples and biological samples such as cells and tissues in living organisms. Also provided are high-throughput screening methods for detecting or screening hypochlorous acid or hydroxyl radical or compounds that can increase or decrease the level of hypochlorous acid or hydroxyl radical in chemical and biological samples.
