Escherichia coli can use N-acetylneuraminic acid (Neu5Ac) as its sole carbon source even if the general outer membrane proteins OmpF and OmpC are not expressed: NanC - a monomeric outer membrane channel - allows Neu5Ac to move into the bacterial periplasm. Recently, a high resolution structure of NanC in two different crystal forms was reported by Wirth et al., J.Mol.Biol., (2009) 394:718 (PDB codes: 2WJQ and 2WJR). Our goal is to determine appropriate ‘baseline’ ionic conditions to study the transport of Neu5Ac through NanC using single channels in lipid bilayers. Measurements of single channel currents showed that NanC has two modes of time dependent behavior (‘gating’). In the many situations we have tested, the modes are not induced or changed by surrounding ionic conditions or voltage. Single channels of NanC at pH 7.0 have: (1) a large conductance (around 100 pS to 800 pS in 100 mM KCl to 3M KCl) that varies with the polarity of the applied voltage; (2) anion over cation selectivity (Vreversal around +16 mV in 250 mM KCl ‖ 1 M KCl); (3) voltage-dependent gating (channel closures above ±200 mV). Single channel conductance of NanC decreases about 50% when HEPES concentration is increased from 100 µM to 100 mM in 250 mM KCl at pH 7.4, consistent with the two HEPES binding sites observed in the crystal structure (PDB code: 2WJR). Studying alternative buffers, we found that phosphate interferes with the channel conductance, whereas TRIS could not be used because it reacts with Ag/AgCl electrodes producing artifacts even in the presence of Agar-KCl bridges. Our further studies of NanC will use no pH buffers, but low concentration (250 mM) salt solutions adjusted to neutral pH 7.0.