Composition for conferring temporary protection from corrosion on metal surfaces comprising an oil-in-water emulsion comprising, in its aqueous phase, at least one compound of general formula I
- in which formula the R, R1 and R2 groups are, independently of one another, a hydrogen atom, a C1 to C20 alkyl group, a C1 to C20 haloalkyl group, with the halogen being chlorine, bromine, iodine or fluorine, a C3 to C6 cycloalkyl group, a carboxyl functional group or a C1 to C6 carboxyalkyl group,
- n is an integer varying from 1 to 3, and
- X is a sulphur or oxygen atom,
- in the form of one of its water-soluble salts,
- characterized in that the said emulsion is obtained by emulsification of an aqueous phase, in which the said compound of general formula I has been incorporated beforehand, with an oily phase.