The invention concerns a method for preparing methyl ethyl ketone azine which consists in: (a) reacting ammonia, hydrogen peroxide and methyl ethyl ketone in the presence of a working solution to form an azine; (b) separating the working solution and the azine possibly containing methyl ethyl ketone which has not reacted and butanol-2; (c) recycling the working solution to step (a) after optional treatment; (d) separating the methyl ethyl ketone and the butanol-2 from the azine. The butanol-2 of the flow in step (d) is either purged or dehydrogenated in MEK and recycled at step (a).