Nd-3divided by ion modified TiO2 sol was prepared by chemical coprecipitation-peptization method. The sol particles were well distributed in colloid system and mean size was 10 nm by AFM analysis. Direct conversion of Nd-3divided by-TiO2 Sol Particles from amorphous to semicrystalline phase was achieved at 62 degreesC and PH 1.0 with 12 h peptizing process. Photocatalytic reactivity of Nd-3divided by-TiO2 sol was evaluated by photodegradation of phenol in solution under visible light irradiation. It was found that concentration decreased from initial 100 mg l(-1) phenol to final 5.29 mg l(-1) phenol and 75.2 mg l(-1) phenol derivatives after 2 h photocatalysis This result indicates that Nd3+-TiO2 nanocolloids exhibited photocatalytic activity in the visible range. Meanwhile. total organic carbon (TOC) value declined from initial 37.1 mg l(-1) to final 29.3 mg l(-1), which indicates the weak capability of photomineralization, but the power of selective photocatalysis. The reaction mechanism of Nd3+-TiO2 sol photocatalysis was proposed as the process of self-sensitization and sub-bandgap overlapping. (C) 2003 Elsevier B.V. All rights reserved.