The hybrid reinforcement effect of surface treated or untreated carbon nanotube (CNT)/glass fiber (GF); on the morphology, mechanical and electrical properties of polypropylene matrix composites were investigated. Surface treatment of the CNTs was performed by using 3-Amino propyl tri ethoxy silane (APTES). Composites were prepared by means of extrusion and injection molding techniques. FT-IR analysis of the CNT samples revealed the successful surface modification of nanotubes after silane treatment. XRD results showed that chemically functionalized carbon nanotubes have the same cylinder wall and crystalline structure with untreated carbon nanotubes. Tensile and dynamic mechanical analysis (DMA) test results revealed that GF and nanotube reinforced hybrid composites exhibited better tensile strength and modulus values than only GF or CNT reinforced composites. According to all these results, it can be concluded that simultaneous usage of glass fiber and carbon nanotube in the composites increases the reinforcing ability of nanotubes in polymer composites. (C) 2014 Elsevier Ltd. All rights reserved.