A rapid and sustainable route for synthesizing a green photocatalyst based on nanometric Cu 2 O clusters dis- persed on TiO 2 (= 2 wt%) was developed. These nanoclusters were synthesized using reducing sugars (0.85 wt %) from aqueous onion waste ( Allium cepa ) as reducing and stabilizing agent. All this under microwave irra- diation. Green photocatalysts produced hydrogen through glycerol photoreforming, ca. 4.7 mmol H 2 /g cat . The recyclability and reusability of these materials were demonstrated and the achieved heterojunction between Cu 2 O and TiO 2 exhibited a bandgap within the visible spectrum at 2.80 eV, showing potential feasibility to solarize this process.