The present invention relates to combinations of a biocidal compound selected from ferric benzoate, aluminium benzoate, barium benzoate and calcium benzoate and the biocidal compound tralopyril, which combinations provide an improved protecting effect against fouling organisms, and the use of these combinations for protecting materials against fouling organisms. More particularly, the present invention relates to compositions comprising a combination of a component (I) and a component (II) in respective proportions to provide a synergistic effect against fouling organisms, whereby component (I) is selected from ferric benzoate, aluminium benzoate, barium benzoate and calcium benzoate, and component (II) is tralopyril； with the proviso that said composition is essentially free of cuprous oxide.
