The methods of synthesizing C-mono and C,C′-bis [alkoxy(organo)silylmethyl]-o(m)-carboranes by the reaction between the corresponding lithium carboranes and chloromethyl(organo)alkoxysilanes have been developed. Various C-mono- and C,C′-bis[chloro- and hydroxy(organo)silylmethyl]-o(m)-carboranes have been obtained from these compounds and their properties have been studied.