This research aims to investigate the influence of nano-silica inclusion on the adhesive proper-ties of an epoxy resin, and its capability in increasing the failure load of the joint with steel sub-strates. For this purpose, single-lap joints manufactured from Stainless Steel 304 (SS) adher-ends bonded together with a thin layer of the silica-reinforced epoxy resin (as the adhesive) are investigated. To improve the epoxy, silica nanoparticles (SNPs) are utilized in three different concentrations (i.e. 1, 2 and 3 wt. %). Failure loads of the joints are extracted by uniaxial tensile loading for the joints including either neat or reinforced epoxy resins. Scanning Electron Mi-croscope (SEM) are used to examine the dispersion quality of nanoparticles into the polymer as well as the hindrance effect of the nano-silica inclusions on the micro-cracks’ propagation or/and their unification. In addition, the fracture surfaces of the joints were investigated so as to relieve the failure type of the joints; whether cohesive or a combination of both adhesive and cohesive types. It was found out that the joint including silica-reinforced epoxy resin at 2wt.% best improved the failure load and changed the debonding mechanism to a fully cohesive type compared to that of the joint comprising the neat resin.