The ruthenium hydride complex RuH(2)(CO)(PPh(3))(3) was found to be an effective catalyst for the cycloaddition reactions of terminal alkynes and azides. In the presence of RuH(2)(CO)(PPh(3))(3), various azides reacted with a range of terminal alkynes to produce 1,4-disubstituted 1,2,3-triazoles with 100% selectivity and moderate to excellent yields.