The rate at which taurine is synthesized in cells is unclear. This study reports the rate constants for taurine, hypotaurine, and other precursor molecules with hydrogen peroxide and superoxide. Raman spectroscopy permitted direct observation of reactions between hydrogen peroxide and the sulfinate and dithiol precursors of taurine. No observable reaction occurred between hydrogen peroxide and the sulfonates taurine or cysteate. Superoxide reacts with hypotaurine, taurine, and cysteate, although hypotaurine engages in rapid side reactions with a tetrazolium dye. Superoxide-produced radical intermediates for hypotaurine and taurine reacted with the nitroxyl radical-containing molecule TEMPONE. Hypotaurine oxidation by superoxide is calculated to occur at a rate sufficient to produce intracellular concentrations of taurine in humans. Hypotaurine's and taurine's reactions as antioxidants are predicted to occur at a fraction of the rate of enzyme-based antioxidant systems, but they may reach similar rates when hypotaurine is present at millimolar concentration in an intracellular compartment.