The mixed oxide SiO2/ZrO2 obtained by the sol-gel processing method adsorbs Sb(V) from acid solution, forming a new phase on the matrix surface designated as SiO2/ZrO2/Sb2O5. The amount of Zr(IV) in the matrix was 8.1 wt.%, corresponding to 0.89 mmol g(-1), and the amount of Sb(V) incorporated in the matrix was 6.3 wt.% (0.52 mmol g(-1)). This material presented a specific surface area, S-BET = 590 m(2) g(-1). The immobilized Sb2O5 is a good cation exchanger and adsorbs methylene blue (MB) cationic dye with an average surface density delta = 1.1 x 10(-11) mol cm(-2) (about 0.07 molecule nm(-2)). The dye is strongly entrapped in the pores of the matrix and it is not leached off in KCl solutions as concentrated as 1.0 M. A carbon paste of the SiO2/ZrO2/Sb2O5/MB material showed a reversible redox pair with midpoint potential E-m = -0.1 V versus SCE. This midpoint potential is not affected by solution pH change between 2 and 7. The immobilized dye mediated NADH catalytic oxidation at ca. 50 mV.