Abstract The effect of H 2O 2, NaClO and Fe on the dissolution of unirradiated UO 2(s) in NaCl 5 mol kg −1 has been studied at neutral to alkaline pH. Dissolution rates have been determined as a function of oxidant concentration. A general equation to correlate both parameters has been obtained: log r = (− 8.0 ± 0.2) + log[ Ox] 0.93 ± 0.07. The values obtained have been compared to those given for spent fuel under the same experimental conditions. The effect of iron is similar in both unirradiated UO 2 and spent fuel with a final uranium concentration around 5 × 10 −8 mol kg −1 which corresponds to the solubility value of UO 2(f) under reducing conditions.