An aqueous composition (C) comprising an NOx reducing agent or a precursor of such an agent, in particular urea, at least one paraffin dispersed in the aqueous phase and at least one compound chosen among: - the hydrocarbyl and mono- or polyalkylene glycol ethers, - hydrocarbyl and polyol ethers, - fatty acid and mono- or polyalkylene glycol esters, - fatty acid and mono- or polyglycerol esters, - and mixtures of these compounds. Such a composition (C) can be used for reducing the formation of deposits in an SCR exhaust system (1) while preventing foaming during the handling of same.
