Mesoporous silicas (SBA-15) were modified by -COOH, -SO3H and -NH2 groups and their tritium adsorption ability from tritiated water under solid-liquid sorption was investigated. The adsorption abilities and separation factor of organic functionalized SBAs were comparable to those of bare SBA. The desorption of water from bare SBA and -COOH functionalized SBA were studied by Fourier transform infra-red spectroscopy using D2O as a probe molecule. An interaction was observed for D2O with -COOH group where the hydrogen bonds became weaker than D2O with bare SBA.