Amphiphilic catalysts are synthesized using NbCl5 in the presence of the CTAB (cetyltrimethylammonium bromide) to generate partial hydrophobicity to the catalysts. The partial hydrophobicity of the niobium oxyhydroxides improved the acetalization reaction of a residual glycerol from biodiesel production by decreasing the interaction between the water molecules and the acid sites of the catalyst. A waste glycerol conversion of 73% with a selectivity to solketal (2,2-dimethyl-[1,3]dioxolan-4-yl)methanol of 95% was obtained. Many reuses of the catalysts showed glycerol conversions between 70 and 80%. (C) 2015 Elsevier B.V. All rights reserved.