Abstract: The present invention relates to the use of thiadiazoles of the type ##STR1## in which R.sub.1, R.sub.2 and R.sub.3 =hydrogen,alkyl groups having 1-4 carbon atomssubstituted alkyl groups having 1-4 carbon atoms which are substituted by halogen, carboxyl, hydroxyl or nitro group,an alkoxyCN, halogen, NO.sub.2 orCOOR in which R=H or alkyl groups 1-4 carbon atoms,and the use of synergistic combinations of thiadiazoles with other biocidal substances as biocides for material protection. The compounds according to-the invention, which are distinguished by a broad, biocidal action spectrum, can be used in particular for wood preservation for preventing the destruction of wood by fungi or bacteria, for the biocidal treatment of plastics and as preservatives or disinfectants. The recommended concentrations for use are 0.01 to 15 percent by weight-preferably 0.1-3.0 percent by weight.

Abstract: The invention relates to thiadiazole compounds of the type ##STR1## wherein R.sub.1, R.sub.2, R.sub.3 arehydrogenalkyl groups having 1-4 carbon atomssubstituted alkyl groups having 1-4 carbon atoms which are optionally substituted by halogen, carboxyl, hydroxyl, or nitro groupalkoxy groupsCN, CF.sub.3, halogen or NO.sub.2,COOR where R.dbd.H or alkyl groups having 1-4 carbon atomswhich, as a consequence of their properties, are extremely effective biocides having broad antifouling properties and are suitable for biocidal finishing of surfaces in contact with sea water and for protecting these surfaces against colonization by marine organisms.The compounds according to the invention are added to or copolymerized into the coatings which protect the surfaces, in 0.1-25% by weight, in particular 5-15%.