A thermoplastic polyurethane elastomer/silica hybrid (TPU/SiO2) was prepared using the sol-gel process. This work was undertaken to investigate the thermal and physical properties of this type of hybrid by employing different catalyst systems during sol-gel processing. Two types of catalyst systems including acetic acid (HOAc) and hydrochloric acid (HCl) were used to prepare so] particles. The mixing of the sol solution and TPU solution was then carried out to form a TPU/silica hybrid. Fourier transform IR spectra and dynamic mechanical properties were recorded to depict the enhanced interfacial interaction. Thermogravimetric analysis was used to determine the actual silica content forming in the hybrid and to evaluate the heat resistance of the hybrid. Mechanical properties such as the tensile strength and cutting strength were investigated at various concentrations of in situ silica. The tensile strength increased at all concentrations of silica. In contrast, the cutting strength decreased, probably because of a reduction of the energy dissipation from silica as physical crosslinks. The HOAc catalyzed system showed better optical properties than the HCl catalyzed system. The fracture surface was revealed through scanning electron microscopy to observe the degree of dispersion of SiO2, which in turn confirmed the results for the optical and mechanical properties. (c) 2005 Wiley Periodicals, Inc.