The AISI 430 ferritic stainless steel was immersed into Neoseptal biocide solution for 480 minutes exposure time at room temperature, and then investigated by Scanning Electron Microscopy. Neoseptal biocide is approved for use in food equipment disinfection, as it is based on hydrogen peroxide, with an action time of 30 minutes. Some researchers consider the residual biocide in the food processing lines between the production batches is a sentinel against undesirable microorganisms. On the other hand, the residual biocide can negatively impact stainless steel surfaces via corrosion. Microscopic analysis showed that the residual Neoseptal biocide is more destructive on ferritic stainless steel surfaces, after 480 minutes than after 30 minutes of exposure time.