A new development to create the surface defect (Ti3+) on TiO2 was reported in this paper and compared to the common methods which must prepare the crystalline TiO2 in the first step prior, and then create the surface defect in the second step. In this work, the surface defect creation was performed in the first step coinciding with the crystalline TiO2 preparation using the sol-gel method. The creation was performed by varying the amounts of oxygen fed during calcination. Based on the CO-temperature programmed desorption (CO2-TPD) and electron spin resonance (ESR) results, the surface defect (Ti3+) substantially increased with the amount of oxygen fed. Moreover, the samples resulting from calcination were used as photocatalysts for ethylene decomposition. The reactivity of those samples was also discussed. (c) 2006 Elsevier B.V. All rights reserved.