Nd2O3-SiO2 nanocomposites with enhanced photocatalytic activity have been obtained through simple and rapid sonochemical route in presence of putrescine as a new basic agent, for the first time. The influence of the mole ratio of Si:Nd, basic agent and ultrasonic power have been optimized to obtain the best Nd2O3-SiO2 nanocomposites on shape, size and photocatalytic activity. The produced Nd2O3-SiO2 nanocomposites have been characterized utilizing XRD, EDX, TEM, FT-IR, DRS and FESEM. Application of the as-formed Nd2O3-SiO2 nano and bulk structures as photocatalyst with photodegradation of methyl violet contaminant under ultraviolet illumination was compared. Results demonstrated that SiO2 has remarkable effect on catalytic performance of Nd2O3 photocatalyst for decomposition. By introducing of SiO2 to Nd2O3, decomposition efficiency of Nd2O3 toward methyl violet contaminant under ultraviolet illumination was increased.