The effect of neutralization conditions of TiO2 acid sol obtained by hydrolysis of titanium tetraisopropoxide (the nature of monovalent cation (Li+, Na+, NH4 +) of electrolyte, chemical nature of a dialyzing solution, and surface modification of nanoparticles with glycidyl isopropyl ether (GE)) on TiO2 dispersion and cytotoxic properties was investigated. The initial TiO 2 and sols after treatment were examined by a set of physicochemical methods: XRD, CS, SAXS, AFM, and TEM. The in vitro toxic effect of nanoparticles was studied on a monolayer of MDCK (Madin-Darby canine kidney) cells by trypan blue staining. It was shown that chemical nature of the electrolyte cation affects sol agglomeration, which increases in a series Li+ > Na+ > NH4 +, and the use of phosphate buffer for sol dialysis facilitates the formation of more uniform disperse systems. Surface modification of TiO2 nanoparticles (TiO2-NPs) with glycidyl isopropyl ether (GE) was found to decrease its toxic effect on the cells.