The article is devoted to investigation of the physico-chemical properties of magnetites in nanocomposites on the textile bases. It studies of the structure and phase composition of nanocomposite materials on the polyamide and viscose textile bases. It is shown that magnetite particles synthesized in textile material with average sizes of 9.4 nm in viscose textile material and 9.7 nm in polyamide textile material. The influence of synthesis conditions on the size of magnetite nanocrystallites in textile material is established.