Abstract: Provided herein are compounds or hypochlorous acid probes which can be used as reagents for measuring, detecting and/or screening, directly or indirectly, hypochlorous acid or hypochlorite. Provided also herein are methods that can be used to measure, directly or indirectly, the amount of hypochlorous acid or hypochlorite in chemical samples and biological samples such as cells and tissues in living organisms. Specifically, the methods include the steps of contacting the hypochlorous acid probes disclosed herein with the samples to form one or more fluorescent compounds, and measuring fluorescence properties of the fluorescent compounds. Provided also herein are high-throughput screening fluorescent methods for detecting or screening hypochlorous acid or compounds that can increase or decrease, directly or indirectly, the level of hypochlorous acid or hypochlorite in chemical and biological samples.