PURPOSE: To prepare an ester compound, in high yield and selectivity, by the oxidative dehydrogenation dimerization of a primary alcohol in an acidic medium using a specific amount of bromous acid or its salt.

CONSTITUTION: An ester compound can be prepared in a yield of ≥90% and a selectivity of nearly 100%, by the oxidative dehydrogenation dimerization of a primary alcohol wherein the residue other than the primary hydroxyl group is preferably paraffinic hydrocarbon group, olefinic hydrocarbon group or polyolefinic hydrocarbon group, in an acidic medium containing mineral acid such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, etc. (especially hydrochloric acid), or an organic acid such as formic acid, acetic acid, oxalic acid, tartaric acid, benzoic acid, etc. (especially formic acid or acetic acid), using ≥0.5mol, preferably 0.5W5.0mol, per 1mol of the alcohol, of bromous acid or its salt.