An alkoxysilane derivative bearing 10-vertex closo-decaborate nanocluster ([B_10H_10]^{2–}) wassuccessfully synthesized and immobilized in SiO2 aerogel matrix. closo-Decaborate-containingSiO2 aerogels showed high specific surface (~750 m2/g), open porosity (~95 %) and extremely lowapparent density (80 mg/cm3) as well as increased thermal stability of closo-decaborate moiety.Despite the low boron content (~1.2 mol.% of boron nanoclusters comprising natural mixture ofboron isotopes), the aerogel nanomaterial demonstrated excellent neutron capture propertiesexceeding lightweight polymer-based analogues. Cell viability assessment indicated thepronounced dose-dependent toxicity of borylated aerogel with respect to malignant cells (U251MG glioblastoma line), and low toxicity with respect to normal cells (dental pump stem cells). Thecombination of the properties of closo-decaborate modified silica aerogels make them goodcandidate material for shielding of patients and healthcare personnel during boron neutron capture therapy procedures.