Abstract: Aqueous disinfectant concentrate which includes succinic dialdehyde, glutaraldehyde and/or formaldehyde, one or more alcohols of limited water miscibility and optionally usual auxiliaries. By diluting with water, a working solution can be prepared from the concentrate. The advantages of the new disinfectant concentrate or disinfectant are the reduced development of odor, an improved material compatibility, an improved microbicidal effectiveness and a clearly increased storage-stability. Furthermore, the activation usual up until now with disinfectants based on aldehyde is superfluous. Preferred application fields are surface and instrument disinfection.