The oxidation of d-galactose by Cu I I has been studied in acetate buffers within the pH range 4-4.75 at 110°C. The observed pseudo-first-order rate constant is given by k o b s = {k a + k b /[H + ] + k c /[H + ] 2 } [gal]/{1 + (k d + k e /[H + ])[gal]} where k a = 2.77 10 - 3 M - 1 s - 1 , k b = (1.22 ± 0.11) 10 - 7 s - 1 , k c = (1.12 ± 0.16) 10 - 1 2 M s - 1 , k d = 2.08 M - 1 ,k e = (2.75 ± 0.33) 10 - 5 . This rate law corresponds to the formation of galactonic acid and Cu I when a 10 fold or higher excess of d-galactose over Cu I I is employed. The results are discussed in terms of a possible mechanism of oxidation of the enodiol of galactose by CuOAc + , present in solution.