interaction of dimethylsiloxanes with sodiumhydroxide. The reasons of high selectivity of the reaction towards 1,5-disodiumoxyhexamethyltrisiloxane were analyzed. It was found that variation of reaction time, type of dimethylsiloxane precursor and ratio between sodiumhydroxide and dimethylsiloxanes in wide range led to the materialization of most part of used sodiumhydroxide in 1,5-disodiumoxyhexamethyltrisiloxane