An original Ni-AlSiO₂ mesoporous catalyst (Si/Al = 6.5, 2.0 wt% Ni) was prepared using a commercial mesoporous non-ordered silica as a support. It exhibited notable catalytic behaviour for the oligomerization of ethylene in both batch and flow mode. Thus, at 150 °C and 3.5 MPa, the catalyst was highly active (up to 130 g of oligomers per gram of the catalyst per hour), selective (C4, C6, C8, and C10 olefins, no cracking products) and stable (high conversion for 9 h on-stream). However, the catalytic performances were slightly lower compared to those obtained with the catalyst prepared using a mesostructured SBA-15 silica as a model support. When nickel-catalyzed oligomerization was coupled with a metathesis reaction catalyzed by MoO_x/(Al)SiO₂ or MoO_x/(Al)SBA-15, ethylene was efficiently converted into propylene. To determine the physico-chemical properties of catalysts, various techniques were used, such as powder X-ray diffraction, N₂ sorption, ²⁷Al MAS NMR, Raman spectroscopy and X-ray photoelectron spectroscopy.