Nickel-titanium (NiTi) rotary endodontic files have been commercially available for decades, but more recent innovations have introduced heat-treated and surface-treated files. This study investigated the corrosion properties of various NiTi files in normal saline and sodium hypochlorite (NaOCl). Ten different file brands of size 40 with a 0.04 taper were subjected to electrochemical testing in 0.9% NaCl (saline) and 5.25% NaOCl at room temperature. The Open Circuit Potential (OCP) was observed for one hour followed by a cyclic polarization test from -300 to 700 mV and back to -300 mV (versus OCP). Non-parametric ANOVA and a pairwise comparison (p<0.05) were used for statistical analysis of the OCP at 1 hour and the corrosion current (Icorr) obtained via the cyclic polarization test. Significant differences (p<0.05) were found between files with respect to OCP and Icorr in both solutions. Nine files exhibited significantly greater (p<0.05) corrosion currents in NaOCl than in saline. Conversely, pitting corrosion was observed in the saline solution but not NaOCl. Weak and/or moderate correlations existed between OCP and Icorr measures in the two solutions. Significant differences in electrochemical properties were observed among the ten brands of files. Overall, there was not a clear trend between conventional, heat-treated, or surface-treated files among open circuit potential or corrosion current in either solution.