New Bronsted solid acid, magnetic silica-supported perfluoroalkylsulfonylimide group was prepared. The as-synthesized functional siloxane oligomer was used to introduce perfluoroalkylsulfonylimide onto the magnetic core under the assist of TEOS, forming multi-layer core-shell structure, which was confirmed by TEM. The inner silica shell protected the acid-sensitive magnetic core from the corrosion of the strong acid; while the outer silica shell attached acid perfluoroalkylsulfonylimide groups. Good thermal stability (< 229 A degrees C) was expectable for the materials by TG analysis. The conclusive acid loadings of 0.61-0.69 mmol/g endowed the materials with efficient catalytic ability for the conversion of cellobiose to glucose (Glu), providing stable 85-91 % Glu yields throughout 3-4 cycles in water at 130 A degrees C. [GRAPHICS] .