A facile and highly efficient method for regioselective synthesis of 1,4-disubstituted 1,2,3-triazoles in good to excellent yields from in-situ-generated azides and terminal alkynes by Cu(I)-catalyzed 1,3 dipolar cycloaddition (the so-called click reaction), is described. The reaction proceeds smoothly in a 1:1 mixture of water and ethanol at room temperature without any additive. The method is a convenient means of preparation of a wide range of triazoles in a one-pot operation via a three-component reaction.