We show the enhanced photocatalytic activity of graphene oxide - Molybdenum trioxide nanocomposites in the visible range synthesized by a simple dispersion method in two steps. In the first step alpha-Molybdenum trioxide was synthesized by acidified Sonochemical method. Then the nanocomposites were prepared by loading alpha-MoO3 on GO. Thus prepared samples were subjected to XRD, UV, PL, Raman, SEM and TEM for structural, optical and morphological studies respectively. The 2-D structure of graphene oxide was confirmed by SEM and TEM. The Raman analysis reveals the presence of D and G peaks of Graphene oxide and also that of MoO3. The X-Ray diffractogram of the nanocomposite indicates the good crystalline nature of the sample and all the peaks were indexed. XPS data conveys the elemental composition of the GO-MoO3 nanocomposite. The BET study reveals a pore size of 4.3 nm for the composite. The as synthesized composites were recognized as a photo catalyst for the photo catalytic dye degradation of Victoria blue dye under various experimental conditions. An explicit control over light harvesting and an enhancement in photo catalytic efficiency was seen by the presence of Graphene oxide. The as synthesized photocatalysts remains chemically and thermally stable and contribute excellent electron transfer mechanism during photocatalytic reactions. The thermal stability of the composites was confirmed by TG-DTA analysis. This work provides new conceit that the as synthesized GO-MoO3 nanocomposites can be efficiently used as high performance photocatalyst for enhancing the degradation of Victoria blue dye under visible light irradiation. (C) 2017 Elsevier B.V. All rights reserved.