The present investigation has emphasized the implication of nano fillers (Al2O3 and TiO2) combined additions in glass fiber reinforced polymer composite on the variation of interlaminar shear strength (ILSS). The experiment has also investigated the effect of crosshead speed during testing and subsequent fracture surface analysis to find out the possible failure modes by scanning electron micrograph examinations. Loss and storage modulus have been experimentally evaluated to support the new findings in the present experimental design. It has been observed that the concurrent presence of nano Al2O3 and TiO2 fillers improves the ILSS. Dynamic mechanical thermal analysis indicated that, the addition of nano fillers reduces the storage and loss modulus of the composites. However, glass transition temperature has not been altered by the nano fillers addition. Box–Behnken design of experiment of surface response methodology has been adopted to optimize the filler content and crosshead speed. A second order mathematical model has been developed and the predicted optimum input parameters are 0.3 wt % Al2O3, 0.15 wt %TiO2, and 500 mm/min crosshead speed. Furthermore, the model predicted results are compared with experimental one and found a close agreement between them. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44274. © 2016 Wiley Periodicals, Inc.