In the present work, the surface of P25 Evonik Degussa TiO2 nanoparticles was modified with silane coupling agent 3-(2-aminoethylamino) propyltrimethoxy-silane (AAPTMS) at low temperature conditions to increase the hydrophilicity and De-NOx ability of the photocatalyst. The modified nanoparticles showed excellent stability in water. Their hydrodynamic diameter and polydisperse index were reduced in comparison with P25 and negatively charged surface was observed. The FTIR spectra revealed -NH2 groups deformation which suggests interaction between surfactant's amino groups (-NH2) with surface hydroxyl groups of TiO2. The thermal analysis depicted combustion of the attached modifier in an elevated temperature range (300-800 degrees C). The AAPTMS-TiO2 particles exhibited higher activity in NOx oxidation in comparison with the bare P25 and remarkable NOx removal ability that was attributed to the surface modification of the nanoparticles with hydrophilic AAPTMS groups. (C) 2015 Elsevier B.V. All rights reserved.