A chemical that kills the residual peroxide in the fiber is termed as a peroxide killer. The residual peroxide present in the fiber will oxidize the reactive dyes, a chromophore that contains the metal ions that leads to tonal variation and sometimes unequal dyeing. In phenomena, the chromophore itself is getting destroyed into a colorless product and lead to pale or white patchy dyeing. So, the removal of residual peroxide is very much essential before starting a good dyeing operation.