The present invention relates to in situ compositions of mono- or diester dicarboxylates, methods employing these in situ compositions, and methods of making these in situ compositions. More particularly, the invention relates to mono- or diester dicarboxylate antimicrobial compositions that can reduce the population of microbes on various surfaces such as facilities, containers, or equipment found in food, beverage, or pharmaceutical processing, or in food, beverage, or pharmaceutical industries, at temperatures between about -70.degree. C. to about 100.degree. C.