Biocidal compositions comprising novel azophenyl compounds which are suitable as fungicidal agents are provided which comprise a carrier and, as active ingredient, a compound of the general formulaR--N.dbd.NX (I)or N-oxides thereof, where R represents a substituted phenyl group, at least one substituent thereof being a group of general formula --NR.sup.1 COR.sup.2, where R.sup.1 represents a hydrogen atom or an alkyl group, and R.sup.2 represents a hydrogen atom or an optionally substituted alkyl, alkoxy, alkenyl, alkenyloxy, phenyl or phenoxy group; and X represents a cyano group, a group --COOH or a salt, ester or amido derivative thereof.