Hypochlorous acid (HOCl) is a neutrally charged molecule. Bacteria have negatively charged cell walls. Just like magnets, molecules with the same charge will repel each other. For example, the negatively charged molecule of bleach (OCl-) is repelled by bacterial cell walls. This is not the case with HOCl which is neutrally charged. HOCl easily penetrates bacterial cell walls. HOCl either oxidizes the cell walls killing the bacteria or enters through the cell walls and destroys the vital components inside the bacteria.