Aqueous redox-flow batteries (RFBs) containing organic redox electrolytes are a promising technology for grid-scale renewable energy storage. Most electrolytes currently under consideration for these RFBs contain charge-storing molecules that are drawn from a narrow collection of molecular scaffolds, and undergo rapid decomposition, which results in high rates of capacity fade. To inform efforts at developing more stable aqueous RFB electrolytes, it is critical that the kinetics of charge carrier decomposition and its relationship to capacity fade are well understood.In this work, we explore a relatively new class of redox-active organic molecules known as azobenzenes as potential charge carriers in aqueous RFBs. The electrochemical properties and cycling performance of a range of substituted azobenzenes are characterized using cyclic voltammetry, chronoamperometry, and constant current-constant voltage cycling. Decomposition products are identified using UV-vis and proton nuclear magnetic spectroscopy, as well as mass spectrometry. We discern the influence of decomposition during flow cell cycling by combining in-line UV-vis spectroscopy with multivariate curve resolution, which allows us to quantify decomposition kinetics and estimate UV-vis spectra of intermediate species/decomposition products. These results are being used to drive de novo computational design of new azobenzene molecules that can eliminate or substantially mitigate the identified decomposition pathways.