The present invention relates to a storage stable biocide composition containing the following components: (a) from 2 wt % to 20 wt % of one or more isothiazolinones selected from the group consisting of methylisothiazolin-3-one (MIT), 1,2-benzisothiazolin-3-one (BIT), and N-methyl-1,2-benzisothiazolin-3-one (M-BIT), (b) from 65 wt % to 97 wt % of at least one biocide selected from the following group: phenoxyethanol, phenetyl alcohol, and phenylpropanol, and (c) from 1 wt % to 15 wt % of water. The invention furthermore relates to use of the composition in order to protect technical materials from spoilage and/or degradation as a result of microorganisms.
