Abstract The selective oxidation of lactose by molecular oxygen has been studied in a batch reactor containing an aqueous slurry of 0.5 kmol m− 3 reactant and 1.0 kg m− 3 catalyst. The in situ Bi promotion of a commercial Pd-C catalyst resulted in 100% selectivity to sodium lactobionate up to conversions of 95% in the pH range 7–10 and at temperatures up to 333 K. Performing the reaction under such conditions that the oxygen transfer to the liquid ...