Lipase B from Candida Antarctica (also known as Candida antarctica lipase B or CALB) was immobilized onto titanium dioxide (TiO 2 ) in a buffer-free, bidistilled aqueous medium. The adsorption isotherm was determined by UV–vis analysis of supernatant solution at 280nm, revealing that in 7h 98% of the theoretical lipase monolayer on the TiO 2 (with 45.7m 2 /g BET area) was achieved.Samples withdrawn from the supernatant immobilization medium were analyzed by Fourier-transform infrared spectroscopy in the 1700–1600cm −1 range (where the Amide I Proteins band appears) in order to obtain quantitative information on the evolution of the secondary-structure elements of the protein. The analysis performed revealed that lipase conformation suffers only minor changes during its adsorption onto TiO 2 . However, water associated to the lipase may interact of several ways with the surface of the hydrated oxide.Characterization of the immobilized biocatalyst (CALB/TiO 2 ) implied SEM, fractal dimension analysis and FTIR techniques. A proposal of lipase-hydrated oxide interaction is presented.