Surface-modified silica holds considerable promise in the development of advanced materials for good mechanical properties and stability. In this work, the surface and mechanical interfacial properties of silicas treated with H3 PO4 , KOH, and C8 H18 are investigated. The effect of chemical surface treatments of silica on surface properties and surface energetics is studied in terms of surface functional values and contact angle measurements. The mechanical interfacial properties of the silica/rubber composites are studied by the composite tearing energy (GIIIC). It is found that the development of surface functional groups leads to a significant physical change in silica surfaces, such as, microstructures and surface free energy parameters. This treatment is possibly suitable for silica surfaces to be incorporated in a hydrocarbon rubber matrix, resulting in improving the tearing energy of the resulting composites.