Quaternary ammonium compounds containing attached to nitrogen at least one high-molecular saturated aliphatic radicle of at least 8 carbon atoms which is interrupted by a sulphur or nitrogen atom, the remaining organic radicles attached to the nitrogen being saturated radicles, are prepared by (1) reacting upon a suitable amine with a reactive ester, e.g. a halide or benzene sulphonyl ester, of the high-molecular aliphatic alcohol containing sulphur or nitrogen in the chain; (2) treating an amine containing the high-molecular substituent with a reactive ester of a saturated alcohol, (3) reacting an appropriate thioalcohol or amine with a saturated amine containing a radicle with a replaceable substituent such as chlorine, and (4) treating a saturated amine having a radicle containing an amino or sulphydryl group with a reactive ester of a saturated alcohol; in each case the product is converted, if necessary, into the quaternary form. The compounds possess bactericidal and fungicidal properties and may be incorporated with inert dispersing agents. The samples furnished under Sect. 2 (5) comprise (1) trimethyl - dodecyl - thiomethyl - ammonium chloride, prepared by heating dodecylthiomethyl chloride, obtained by introducing hydrogen chloride into a mixture of dodecylmercaptan and formaldehyde, with trimethylamine; (2) dimethyl-dodecyl-dodecyl-thiomethyl-ammonium chloride, formed by heating dodecylthiomethyl chloride with dimethyldodecylamine; (3) dimethyl - hydroxyethyl - dodecylthiomethyl - ammonium chloride, obtained by stirring dodecylthiomethyl chloride with dimethylaminoethanol; (4) methyl-diethyl - dodecylthioethyl - ammonium iodide, prepared by heating methyl iodide with diethyl - dodecylthioethylamine, which results from the interaction of sodium dodecylmercaptan with diethylaminoethyl chloride; (5) trimethyl - decylmethylaminoethyl - ammonium bromide, which is produced by heating trimethylamine with methyldecylaminoethyl bromide, the latter being formed when the reaction product of methyldecylamine and ethylene bromhydrin is treated with hydrogen bromide; (6) trimethyl - dodecylmethylaminoethyl-ammonium iodide, prepared by heating methyldodecylamine with dimethylaminoethyl chloride and treating the resulting dodecyl-trimethyl-ethylenediamine with methyl iodide. The Specification as open to inspection under Sect. 91 describes the high-molecular aliphatic radicle as preferably containing 8--20 carbon atoms and states that substituents, such as hydroxyl, alkoxy and amino groups and halogen atoms, may be present therein. It further states that the other saturated organic radicles are preferably lower alkyl groups, but may also comprise alkyl groups of 8--18 carbon atoms or cyclo-aliphatic groups, e.g. cyclopentyl and cyclohexyl groups. The preparation of the following compounds is also described: (1) tributyldodecylthiomethyl - ammonium chloride from dodecylthiomethyl chloride and tributylamine; (2) trihydroxyethyl - dodecylthiomethyl - ammonium chloride from dodecylthiomethyl chloride and triethanolamine; (3) methyl-diethyl-octylthioethyl-ammonium iodide from diethyl - octylthioethylamine, prepared by reacting octylthioethyl chloride with diethylamine, and methyl iodide. Finally, it is stated that the quaternary ammonium products in the form of their hydrohalides may be converted into salts with nitric, sulphuric, alkyl- and phenyl-sulphonic, phosphoric, formic, acetic, lactic, citric, tartaric, benzoic and salicylic acids, or may be treated with caustic alkali to give the free bases. This subject-matter does not appear in the Specification as accepted.