Quinolines are a class of important heterocycles that are traditionally known as antimalarial agents and more recently as key pharmacophores in protein kinase inhibitors for cancer treatments. Such beneficial biological activities make quinolines attractive targets for both synthetic and medicinal chemists. Among a variety of methods for constructing the quinoline ring, the Friedländer synthesis has proven to be one of the most powerful and versatile tools (a review: Cheng, C.-C.; Yan, S.-J. Org. React. 1982, 28, 37). In a recent communication (Li, A.-H. et al, Org. Biomol. Chem. 2007, 5, 61), we reported a highly effective and practical one-pot Friedländer quinoline synthesis utilizing inexpensive reagents, i.e., iron, HCl, and KOH. In this process, o-nitroarylcarbaldehydes were reduced to o-aminoarylcarbaldehydes with iron in the presence of catalytic amount of HCl (aq) and subsequently condensed in situ with respective aldehydes or ketones to form mono- or di-substituted quinolines in good to excellent yields (27-99%). This novel procedure worked well with a wide variety of (het)aryl o-nitro carboxaldehydes and carbonyl compounds, tolerating a wide range of functionalities. In this report, we disclose the full results from our investigation, including the scope and limitations of our one-pot Friedländer synthesis protocol.