Clinical needs caused the new method development for SC determination. SWV method for SC standard, tablet and in human serum in 0.05 M NaHCO3 is applied. In 0.1 M H2SO4 for SC standard and tablet catalytic effect of Au/Cys is observed. SWV is more sensitive than HPLC and can be used for very low concentrations of SC. Microscopic characterization of the morphology of the used electrode surfaces.