The invention relates to a method for preparing disinfected seed, a use of a treatment composition, and an apparatus for disinfecting of seed. The method of the invention comprises contacting seed with a treatment composition comprising at least one disinfecting agent and/or a liquid component, and thereafter or at least partly simultaneously, exposing said seed to a treatment atmosphere for an exposure time of at least 1 second, wherein the treatment atmosphere has a relative humidity of at least 50% and a temperature of at least 40° C.