The uptake of dissolved oxygen by betanin was measured to better understand the role of oxygen in the degradation of this pigment. Measurements of the simultaneous disappearance of betanin and oxygen from solution suggested over all second-order reactions kinetics. The uptake of oxygen was pH-dependent, with increased uptake occurring above and below the pH range in which betanin is most stable (pH 4.0–6.0). The addition of cupric ion increased the uptake. Copper(II), iron(II), and iron(III) ions in the concentration range 0.05–1.0 mM were evaluated for their effects on the rate of betanin degradation. At a given concentration, cupric ions had the greatest influence and ferric ions the least. Increasing levels of cupric ions caused a rapid increase in the rate of betanin loss until a plateau in the rate was reached at a concentration of approximately 0.1 mM. In the presence of cupric, cuprous, and mercuric ions, the colour of betanin solutions instantly changed, suggesting the formation of metal-pigment complexes. These spectral changes could be reversed by acidification and/or the addition of EDTA.