ZnO quantum dot (QD) is prepared in a soft chemical route by ageing process and successfully embedded on reduced graphene oxide (rGO) surface using solvothermal method as confirmed by XRD, TEM and Raman studies. Due to charge transfer from the lowest unoccupied molecular orbital of the rGO layer to the conduction band of ZnO, the luminescence of rGO is also found to be quenched in ZnO/rGO composites. A brief systematic study of photocatalytic behavior towards degradation of various toxic medical and textile dyes, like Safranin O, Methylene blue and Rhodamine 6G by ZnO QD and ZnO/rGO composites are showcased in this work. As a result of high surface to volume ratio, ZnO QD showed good photocatalytic activity towards degradation of different dyes under ultraviolet (UV) irradiation. A composite with ZnO and rGO in 3:1 wt ratio degraded almost 100\% of dyes under UV irradiation within 15, 25 and 30 min, showing good efficacy in dye degradation. Photoluminescence lifetime measurement revealed the charge transfer process from rGO to ZnO resulting a Prompt recombination of the UV light induced electron-hole pair in ZnO/rGO composite. © 2018 Elsevier B.V.