This study reports on the thiourea dioxide catalyzed transfer hydrogenation of diverse C=N-containing heterocyclic compounds with Hantzsch ester as the hydrogen source. With this cost effective and readily available catalyst, a wide range of 2-substituted quinolines, 3-substituted-2H-1,4-benzoxazines and 3-substituted-2H-1,4-benzothiazines were efficiently reduced to the corresponding tetrahydroquinolines, dihydro-2H-benzoxazines and dihydro-2H-benzothiazines under mild conditions. This study reports on the first thiourea dioxide catalyzed transfer hydrogenation of 2-substituted quinolines, 3-substituted-2H-1,4-benzoxazines and 3-substituted-2H-1,4-benzothiazines with Hantzsch 1,4-dihydropyridine as the hydrogen source.