Disclosed is an antimicrobial composition containing an active halogen-containing component having a source of an active halogen and having an elevated pH, which is mixed with an acidic component. An acidic component is added in an amount to the active halogen-containing component to reduce the pH of the antimicrobial composition. When the pH of the active halogen-containing composition is reduced, the resulting composition has been discovered to be effective as a disinfectant and, particularly, as a sporicide. Application methods for applying the composition are also described.