Abstract: A procedure for the expedient synthesis of well-characterized Cu(I) oxide nanoparticles (Cu2ONPs) from Cu(II) salts by employing Rice (Oryza sativa) as a cheap and ready source of reducing as well as stabilizing agent has been demonstrated. The judicious choice of rice as a catalyst has helped in the symbiotic combination of two events: viz., acidic hydrolysis of starch to form glucose and the subsequent formal reduction of Cu2+ by the in-situ generated monosaccharide reducing sugar (glucose) under the alkaline condition to produce Cu2O. Further, rice was also found to be effectively stabilizing the nanoparticles from agglomeration. Optical and microscopic techniques were suitably employed for the characterization of the nanoparticles of approximately 10 nm size. Furthermore, the specifically generated nanoparticles were found to be active catalysts in an aqueous medium for Azide-alkyne Huisgen cycloaddition (Click reaction) under base free condition via one-pot multi-component addition for the synthesis of mono-, bis- and tris-1,2,3-triazoles in good to excellent yields. Graphic abstract: Cu2ONPs synthesized using hydrolysed Rice, an active catalyst for synthesis of mono-, bis- and tris-1,4-disubstituted 1,2,3-triazoles via one pot multicomponent reactions in water.[Figure not available: see fulltext.]. © 2020, Indian Academy of Sciences.