We prepared a new carbon film electrode by the electron-cyclotron-resonance (ECR) plasma sputtering method. The film is amorphous-like and different from the glassy carbon (GC), highly oriented pyrolytic graphite and diamond films that have previously been studied for use as electrode materials. We used cyclic voltammetry (CV) and flow injection analysis (FIA) with amperometric detection to compare the electrochemical properties of an ECR-sputtered carbon (SC) film electrode with those of a GC electrode and carbon film deposited by thermal chemical vapor deposition (T-CVD). The ECR-SC film electrode exhibited better electrochemical properties than the GC and T-CVD carbon electrodes, namely, a lower background current, a wider working potential window, and better reproducibility. CV with the ECR-SC film electrode did not reveal any large reduction in rho-nonylphenol (NP) and other alkylphenol (AP) peaks. In contrast, we observed a clear reduction in the CV and FIA peaks when we measured NP with GC and T-CVD carbon electrodes, indicating that there was much less deactivation from the NP oxidation products on the ECR-SC electrode surfaces. The NP calibration curve at the ECR-SC electrode in a flow system showed a linear concentration range of 0.125-10 muM with a detection limit of 50 nM (S/N = 3).