Graphical abstract Liquid phase oxidation by molecular O 2 of different primary alcohols and aldehydes to corresponding aldehydes and carboxylic acids with high yields can be accomplished in the absence of any solvent using a reusable magnesium oxide supported nano-gold catalyst. Highlights ► The Au/MgO catalyst shows very good performance in both processes. ► It shows very high activity under solvent-free conditions. ► It is easily separable and reusable in both the reactions. ► Both the oxidation protocols are green/environmentally friendly.