The present invention relates to new, highly efficient anti-microbial compositions comprising essential oils, metal ions, organic acids and detergents. Bacteria-containing samples treated with the complete synergistic disinfecting composition according to the invention (A or B or C or D + O) do not show any living cell colonies, indicating that under these conditions all microorganisms were killed. Thus it is proven that the synergistic mixtures of the compounds according to the invention show a very effective antimicrobial effect.