In this paper, the interaction between five biocides(commercial) and two ethylsilicate consolidants for stone monuments, reacted in different sequence, has been studied. Through the structures, weight and gelation time of mixture of biocides and consolidants have been evaluated the reactivity of biocide alone, the reactivity of consolidants and biocides, the reactivity of consolidants and dried biocide, and the reactivity of ethylsilicate gel and biocides. The tested biocides show quite different properties from those of consolidants; after evaporation, some biocides are remained white salt crystals, another need the long time for evaporation and one biocide shows pale brown color. The results have shown an interaction of the tested products each other in some application sequences of the products. When the application of liquid state biocides with consolidants, it was noted that some biocide seem to interfere with the formation of gel due to reaction of consolidants and water and salts in biocides. In the reaction of ethylsilicate with dried biocides have shown a heterogenous gel(transparent layer with ethylsilicate alone and white layer which is mixed biocide and ethylsilicate) and many cracks in product due to the different shrinkage, thus the products don't play a role as consolidants. There is no change in structures and color in reaction of the gas state biocide and ethylsilicate gel.